Ricardo Fuller's third minute goal was enough to settle this contest and leave Gillingham to reflect on their sixth home defeat of the season.
The game marked the halfway point in the first division programme and Gillingham have the third worst home record in the division - only Bradford City and Wimbledon have lost more games at home.
These two teams are old rivals from numerous meetings over the years, but Gillingham had the edge at Priestfield after handing out two big drubbings in recent seasons.
However, Preston have recovered from a poor start and this third away win takes them to the fringe of the play-offs ahead of next week pre-Christmas Lancashire derby against Burnley.
Craig Brown emphasised his intentions by naming an attacking formation, but Fuller needed no second opportunity to make the most of some woeful Gillingham defending which was the key to a frustrating afternoon for the home fans.
Gillingham failed to clear a routine defensive header and the ball bounded nicely for Fuller who rounded keeper Jason Brown to shoot low into the empty net for his 11th of the season.
How Richard Cresswell wished he could have been in the same position to break his goal famine which now exceeds 1,000 minutes.
The former England Under-21 striker thought he had scored ten minutes before the break with a simple close-range header, but his luck was out again as referee Ray Olivier ruled it out as assistant Steve Chittenden waved for an infringement on the far side.
Cresswell looked to the skies in huge disappointment but at the other end goalkeeper Jonathan Gould and his defenders stopped everything Gillingham could throw at them on a wet and windy afternoon in Kent.
Nobody could fault Gillingham's approach work on either flank but they were found wanting in front of goal as they lacked a cutting edge with top scorer Marlon King now gone and Rod Wallace and Tommy Johnson both ruled out by injury.
One felt for Mamady Sidibe who was playing with a slight hamstring problem. He did his best but had no luck. He looked to have been brought down in the area in the second half and then picked up a knee injury but all in all it was a frustrating afternoon.
Four minutes were added on at the end but Preston were happy to hear the final whistle and complete a third away win and their first on the road since mid-October.