Doncaster have been facing a battle against relegation all season, whereas North End have been aiming for the top six, but there was little to choose between the sides for most of the match.
In fact Doncaster looked the better side for long periods and had most of the play up to Preston taking the lead in the 26th minute.
James Hayter had a glancing header saved in the seventh minute and Dean Shiels was unlucky to see another header come back off the post with visiting keeper Andy Lonergan well beaten in the 24th minute.
But it was Preston who took the lead with a goal out of the blue two minutes later.
Eddie Nolan made ground on the left before crossing into the middle where big Chris Brown headed home powerfully from close range.
Preston had more of the play for the rest of the half, but Rovers defended stoutly and Billy Jones was out of luck when he headed fractionally over from Chris Sedgwick's cross on the half-hour mark.
Doncaster came out for the second half with all guns blazing, but could not get the equaliser their efforts deserved.
Hayter had an overhead kick blocked and then Shiels had a shot deflected just wide following a 46th minute goalmouth scramble.
Lonergan just beat Lewis Guy in a chase for the ball a couple of minutes later, before Neil Mellor got the ball in the net at the other end only to have the effort disallowed for pushing after 55 minutes.
Doncaster's efforts were in vain when Preston put the issue beyond doubt in the 72nd minute when Mellor scored from close range, after latching on to a shot from Jon Parkin that had been going wide.
Rovers never looked like battling back as they slumped to their fourth successive home defeat.