Lee Hughes fired the Latics ahead with his 17th goal of the season, but Lucciano Becchio hit back as the visitors gained a well-deserved reward for their attacking play.
Oldham, who were wearing a bright pink kit in support of a local breast cancer charity, had keeper Greg Fleming to thank for two excellent saves, while former Leeds captain Sean Gregan was rock solid in the heart of their defence.
Leeds midfielder Neil Kilkenny also impressed against his old club, but managers John Sheridan and Simon Grayson agreed that a draw was the right result from a tense roses clash.
Oldham had two escapes in the first nine minutes as Daniel Jones made a perfectly-timed tackle to stop Becchio going clean through and then seemed to block a cross with his arm.
Leeds' penalty appeals were ignored and Oldham almost made the breakthrough moments later when Hughes was blocked just eight yards out.
Controversy came midway through the half when Becchio felled Gregan with an elbow but was only booked for the challenge.
The Yorkshire club soon went close through Jermaine Beckford, who guided his header off target from Kilkenny's pinpoint cross.
Another Leeds chance went begging with Bradley Johnson's weak finish before Robert Snodgrass headed straight at the keeper from ten yards.
United continued to edge possession after the break, but Fleming was allowed a second comfortable save when Richard Naylor met a Johnson cross.
Oldham took advantage in the 51st minute when Jones moved up from left-back and swung in a deep centre.
Deane Smalley's touch sent the ball looping back across goal where Hughes directed his volley through the legs of keeper Casper Ankergren from an acute angle.
Leeds nearly equalised straight from the restart as Becchio's header forced Fleming into an acrobatic tip over the bar.
From the resulting corner, Becchio was given a free header six yards out and the ball crashed in off the woodwork.
Leeds came closest to snatching a winner as Fabian Delph fired towards the bottom corner, but Fleming dived to the rescue for Oldham with another fine stop.