The Airtricity Premier Division leaders could not break the deadlock in a close game at Thomond Park, but moved three points clear of Dundalk at the top of the table
A slow start saw little of note for the first 10 minutes. Killian Brennan had an early effort for the visitors, but couldn't direct his shot on target. A poor back pass from Daryl Kavanagh almost allowed Curran in on goal, but Saints goalkeeper Brendan Clarke was out quickly to clear the danger.
St Pat's were forced into an unplanned substition when Shane McFaul was forced off injured after just 20 minutes. Most of the action was happening at Clarke's end, but the keeper was relieved to see Samuel Oji's shot rippled the side-netting after David O'Leary whipped in a free-kick. Clarke had to be alert moments later to deny Craig Curran, diving low to keep out the striker's header and keep the game scoreless at half-time.
The visitors should have taken the lead just after the interval, but Kavanagh drove his shot over after being put in on goal by Conan Byrne. The midfielder delivered another fine ball into the area soon after, but Christy Fagan also failed to hit the target with his header.
Both teams had chances to open the scoring midway through the second-half, but O'Leary couldn't keep his shot down after a fine ball from Robbie Williams, while Kenny Browne had a shot cleared off the line before Barry Ryan denied Fagan with a great save.
St Pat's almost snatched the winner right at the end, but Conan Byrne was denied by the post after Anthony Flood picked him out at the edge of the area. A late goal would have been harsh on Limerick, who defended well throughout and deserved the point.
The draw sees St Pat's move three points clear of Dundalk at the top of the table, but their title rivals could go level if they can defeat Drogheda United in Sunday's Louth Derby.