The territory's biggest public hospital paid $10.5 million to patients injured under the care of its medical staff in the latest financial year.

Cases brought forward in the ACT legal courts as part of a blitz on delayed matters and a few large claims made by patients with serious, and possibly lifelong, injuries caused the spike in compensation.

An investigation looking into the extent and specifics of medical negligence in the ACT has found Canberra Hospital paid $7.5 million for its mistakes in 2011-12 and $1.6 million the year before.

However, money paid to patients, totalling $29 million at Canberra Hospital in the past five years, is only part of the cost.

''These figures do not include costs incurred in investigating matters which do not eventuate in a claim or legal defence costs,'' an ACT Health spokeswoman said.

The vast majority of the money paid is covered by insurance underwritten by taxpayers.

And the excess paid by the hospital gradually increased in recent years until the bill peaked in 2012-13 at $675,000.

There are often long delays for patients suing for compensation and some of the payouts in the past five years have been made for cases stretching back to the late 1980s.

Earlier this year The Canberra Times reported more than 40 territory health professionals had restrictions placed on them by the watchdog to protect the public.

Latest available figures show Australia's health watchdog has received 100 complaints about doctors in 2011-12, or a 25 per cent increase on the previous year.

Figures not yet made public also show the watchdog checked the backgrounds of 812 Canberra health professionals in 2011-12 and 46 of them, or 6 per cent, had criminal histories.

Personal injury lawyer Mark Blumer said he was surprised and concerned by the number of medical negligence cases coming through.

''It does not seem to be abating,'' Mr Blumer said. Canberra lawyers interviewed said the vast majority of cases regarding medical mistakes were settled with a payout to the patient before they went to trial.

Sometimes documents did not even need to be filed in court. Because there are few medical negligence trials, it means the public rarely finds out about most of these cases.

Legal firms specialising in personal injury reported high success rates, mainly because of strict vetting processes before they took cases on.

However, lawyers also said if the case went to trial, the chance of victory for the patient was ''a toss of the coin''.

Personal injury lawyers are using their websites to advertise to potential patients and specify a range of cases they take on, including surgical negligence - such as swabs left inside patients or wrong body parts operated on, as well as infections, wrongful death, misread X-rays and ultrasounds, and incorrect diagnoses. There also appears to be a focus on damage to infants and babies, which can prompt huge payouts because of projected lifelong expenses. This includes mismanaged pregnancies and complications during labour.