Derry City got the point they needed to secure European football for next season on a night of high drama at Richmond Park.
Sean O'Connor put St Pat's ahead on 30 minutes before goalkeeper Chris Bennion gifted the equaliser to Stephen McLaughlin on 73 minutes.
McLaughlin pounced from behind to disposes Bennion and shoot into the unguarded net.
Stephen Bradley could have won the game for the home side on 90 minutes but his penalty crashed off the post.
St Pat's boss Pete Mahon made six changes to the side that lost to Shelbourne in Monday night's FAI Cup semi-final replay.
One of those was the enforced one for the goalkeeper's gloves, with Bennion starting in place of the suspended Gary Rogers, who was sent off against Shels.
Bennion was kept busy by Derry in the opening minutes with several attacks on goal but Bennion was equal to the task.
On seven minutes he made a fine save when Derry's Kevin Deery shot from the left, just outside the box.
St Pat's, playing their 55th game in all competitions this season, were much improved from Monday night and had their first chance of the night on eleven minutes.
Dave Mulcahy sent an-inch perfect pass to the fit-again Sean O'Connor on the left but Danny Lafferty darted back to clear O'Connor's shot off the line.
Pat's went close again on 25 minutes when O'Connor connected with Paul Crowley's pass and shot well but was denied by an excellent save by Derry goalkeeper Ger Doherty.
Pat's looked the more likely of the two sides to score and took the lead on the half hour. O'Connor, celebrating his 28th birthday, collected a pass from David McMillan and chipped a cracking left-footed ball over the advancing Doherty and into the net.
Daryl Kavanagh wasted a chance to double the Pat's lead on 56 minutes when he tried to finish a wonderful Pat's move that had developed along the right wing.
Kavanagh took possession of the ball inside the area but then slipped with the ball at his feet, much to the annoyance of the Pat's fans who saw the former Waterford and Limerick man do the same thing twice within the space of a minute against Shelbourne on Monday night.
Derry were back on level terms on 73 minutes when a big mistake by Bennion allowed McLaughlin in to score.
The Pat's goalkeeper dropped the ball from his hands in preparation to kick the ball upfield but didn't realise that McLaughlin was standing right behind him. When the ball hit the deck McLaughlin saw the opportunity, rushed around Bennion and took possession of the ball before shooting into the now unguarded net.
Bradley could have won the game for Pat's at the death but his penalty hit Doherty's right hand post.