They had midfielder Steve Jennings sent off right on half-time but regrouped to grab a shock lead in the final quarter.
From 35 yards Paul McLaren pushed forward a free-kick. There was a gap between the keeper and his left-hand post and it was filled by Antony Kay's header.
From a rugged aimless affair, the match at last took on a focus and seven minutes later Bristol salvaged a draw, with a Craig Disley header taking their record to one defeat in 15. But it was far from an impressive performance.
Tranmere also had an unbeaten run to defend since Rovers beat them six weeks ago but that was not the main thought on their minds.
Manager Ronnie Moore had complained Bristol "bullied" them at their earlier meeting and his players seemed determined to get in their retaliation first.
In seven minutes after the half hour they picked up yellow cards for Jennison Myrie-Williams, Kay and McLaren.
Worse was to follow for just before half-time, a blatant trip on home midfielder Chris Lines saw Jennings red-carded.
Tranmere chose to run with just one up front for the second half, but the collective red mist had lifted and Bristol simply ran out of ideas until they made three changes with 18 minutes to go.
They sent on a new attack in Richard Walker and Sean Rigg and at last looked like breaking through.
Two of the subs, Sammy Igoe and Walker, combined down the right and with Stuart Campbell providing the final ball towards the far post, Disley stooped to claim the equaliser.