Matt Fryatt had a 20-yard shot saved at the near post by Preston goalkeeper Andy Lonergan low to his right in the first minute.
Leicester made it 1-0 in the sixth minute when Dany N'Guessan dispossessed Paul Parry and his right-wing cross found Nicky Adams, who curled the ball into the top left from 15 yards.
In the ninth minute a right-foot in-swinging corner by Adams was saved.
Fryatt's left-wing right-foot shot was saved after 13 minutes at the near post for a corner.
Chris Brown equalised for Preston a minute later. Preston left-back Eddie Nolan found Brown and he scored from just inside the box into the bottom left far corner of the net.
Brown had a seven-yard shot saved by Leicester goalkeeper Chris Weale after 18 minutes.
Nolan had a shot saved after 26 minutes and Adams' 18-yard shot was saved two minutes later.
Brown and Nolan had efforts saved in the 38th and 41st minute.
Chris Sedgwick's left-wing right-foot corner was saved a minute before half-time.
Sedgwick's 63rd minute shot was saved and then a left-foot right-wing corner by Parry found Brown and his effort was saved.
Brown made it 2-1 with his fourth goal of the season after 65 minutes. He headed home from close range from a Nolan left-foot deep left wing cross.
Lloyd Dyer replaced N'Guessan after 74 minutes and three minutes later Richard Chaplow and Neil Mellor came on for Darren Carter and Stephen Elliott.
Paul Dickov and Yann Kermorgant replaced Matt Oakley and Paul Gallagher after 78 minutes.