Frank Ferrante's life has been inextricably intertwined with that of one of his comic idols, Groucho Marx, for more than 30 years. He's donned greasepaint and glasses to play Groucho more than 3000 times in more than 500 cities. And he's done something Groucho, for all his many accomplishments, never did: tour Australia.

Groucho Marx (1890-1977) was an American comedian and actor whose long career encompassed vaudeville, Broadway, movies, radio, television and books. His distinctive stage and screen appearance - thick eyebrows, glasses and moustache, cigar, and stooped walk - and comic persona - a quick-witted, sharp-tongued rogue - combined to form an indelible comic creation.

Ferrante - a Californian of Italian Catholic stock, unlike the New York Jewish Marx - first encountered the world of Groucho and his most enduring onscreen companions, brothers Harpo and Chico, as a boy when he saw their 1937 movie A Day At the Races on television. He was smitten by their brand of comedy, a heady blend of wisecracks, puns, slapstick and smatterings of surrealism.

He first played Groucho in 1984 as part of his drama studies at the University of Southern California. Groucho's playwright son Arthur saw the performance and cast the 23-year-old Ferrante to play his father in his biographical play Groucho: A Life in Revue, in which Ferrante in the title role aged from 15 to 85. He performed in the show in New York, winning a Theatre World Award, and London.

The current show, An Evening With Groucho, is one Ferrante devised himself, going right back to that university show for inspiration, most of it based on material written or performed by Groucho, and has been touring and refining for many years over 2500 performances. A lot of it is improvised or changed on the fly and there's a fair bit of audience interaction, so every performance is different - again, taking its cue from the Marxes, who were notorious for straying from the script at will and wreaking havoc on stage. During the run of one of their shows, its co-writer George S.Kaufman was in the wings listening to a friend when he suddenly excused himself for a moment and left him. When Kaufman returned, he said, "Sorry I interrupted your story, but I thought I just heard one of the original lines."

Ferrante says it's not intended to be simply a tribute show or an impersonation but an evocation of Groucho for people who never got the chance to see him live and in his prime. It's intended to appeal to existing fans as well as people who might never have heard of the Marx Brothers - Ferrante says his audiences range from grandparents to children, introducing new generations to the joys of this merry brand of Marxism.

"It's like imagining him performing during the gap between the movies Duck Soup (1933) and A Night at the Opera (1935) and what it might have been like if he'd been on stage then, talking and singing songs."

Ferrante doesn't limit himself to the strictly chronological - he ranges freely over the course of Marx's life and career.

Subjects might include the tough early days touring in vaudeville with Groucho's brothers (also including Zeppo, who left the act after a few movies, and Gummo, who never went to Hollywood), or the intellectual and cultural aspirations and achievements of the young Julius (his real name).

He had wanted to study and be a doctor but his pushy stage mother Minnie made him abandon formal education while he was in primary school and join the act so he ended up self-taught, a voracious reader, a fan of Gilbert and Sullivan (he played Ko-Ko in a television production of The Mikado) and a prolific letter writer: a published volume of his correspondence includes exchanges with such luminaries as the poet T.S. Eliot.

Ferrante also performs some of the songs associated with Groucho Marx such as Lydia the Tattooed Lady from the 1939 movie At the Circus and Hooray for Captain Spaulding from the 1928 stage show Animal Crackers and its 1930 film adaptation.

The latter was later used as the theme tune of Groucho's longrunning TV quiz show You Bet Your Life (1950-1961) - which had begun on radio in the late 1940s - where the questions were less important than Groucho's humorous interactions with the contestants. Although he was fed some lines by the show's writers, who conducted pre-interviews with the contestants, Groucho didn't meet any of the people taking part beforehand to preserve spontaneity.

It gave rise to a legendary apocryphal story involving a mother with a large number of children (about 18). Groucho asked why she had so many offspring and was told, "I love my husband". He replied, "I love my cigar, but I take it out of my mouth once in a while."

Although Marx in later years denied it happened and no such exchange survives on film, Ferrante is not so sure. Others involved said it did occur and Ferrante thinks it may have taken place on the radio and been censored for broadcast: the show was prerecorded both for time and to make sure risque moments like these were removed.

Ferrante's favourite Marx Brothers film is Duck Soup (1933) with A Night at the Opera (1935) coming in second. "I got to meet Groucho when I was a boy," Ferrante says.

It was 1976, he was 13 and his father took him to where the then 86-year-old Groucho was making a public appearance to promote a book.

"I sat at Groucho's feet and he started mumbling. He was wearing his trademark beret and had thick glasses on," Ferrante says.

"He was not well, he'd suffered a couple of strokes," Ferrante says.

It seemed a little sad. Then somebody in the audience asked, "Are you making any more Marx Brothers movies?" and Groucho replied. "No, I'm answering stupid questions."

People laughed, relieved as well as amused: this was was the Groucho Marx they had hoped for - acerbic and quick-witted. A woman asked, "What are you dreaming about?" and he looked at her and shot back, "Not you!"

Playing Groucho Marx is not Ferrante's whole life, of course: he likens what he does to fellow American actor Hal Holbrook, who's made an even longer career of enacting Mark Twain on stage. But like Holbrook, that's only part of what he does: Ferrante is busy as an actor and director.

Still, Groucho keeps sneaking back in: among the other roles Ferrante has played is Captain Spaulding in several productions of the aforementioned Animal Crackers.