Scotland suffered a triple setback ahead of their tour of Australia, Fiji and Samoa after David Denton and wing Lee Jones were ruled out through injury on Thursday while lock Jim Hamilton was banned.
Edinburgh No 8 Denton has been sidelined with ankle ligament damage while club colleague Jones has a fractured shoulder blade.
Hamilton will miss the tour after the Gloucester lock received a seven-week ban from England's Rugby Football Union following a brawl with London Irish hooker David Paice during the Premiership game between the clubs on Saturday.
Under rugby union's principal of reciprocity, a disciplinary ban imposed by one national governing body makes a player unavailable for all matches while he is banned.
The triple blow for Scotland came ahead of a tour where Andy Robinson's side will look to revive their fortunes after a dire Six Nations saw them finish bottom of the table having lost all five of their matches.
Scotland team doctor James Robson said Thursday: "Lee suffered the fracture in the Heineken (European) Cup semi-final loss to Ulster last month.
"Injuries of this nature typically resolve over the course of six to eight weeks, so he will not be available for the tour."
Robson added: "David sustained the ankle injury in the final game of the league season against Treviso last weekend and subsequent scanning of the joint revealed damage to the ligaments.
"Following consultation with John McKinley, the ankle specialist at Spire Murrayfield Hospital, David will not require surgery but will now embark on a prolonged period of rehabilitation which will rule him out of the summer tour. His estimated return would be between eight to ten weeks."
Scotland are due to announce their squad for next month's three Test tour on May 16.
They are due to play Australia in Newcastle, New South Wales on June 5, Fiji in Lautoka on June 16 and Samoa in Apia on June 23.