Preston have now gone nine games with only one win and six points from a possible 27.
Walsall had a chance in the first minute when Neil Emblen had a 25-yard shot saved by Andy Lonergan who pushed the ball around the post for a corner.
After 75 seconds Walsall made in 1-0 when a Paul Merson corner was met by Matt Fryatt in the six yard box and his header went into the top of the net.
David Healy shot tamely at James Walker and then Simon Lynch had a header from seven yards cleared off the line by Mark Wright.
Rob Edwards then had to go off with a neck spasm and was replaced by Jeff Smith making his home debut.
Craig Burley was booked for foul on Richard Cresswell after 43 minutes, before the former York star had a goal disallowed for hand ball.
After the break, Healy shot again at Walker and then Matt Carbon fouled Cresswell in the penalty area to earn a booking and concede a penalty, which Graham Alexander hit right footed into the top corner to make it 1-1.
Walsall made it 2 - 1 after 65 minutes when Man of the Match, Merson hit a right foot cross which Wright headed from five yards into the centre of the goal.
In the closing stages Alexander shot straight at Walker and then Cresswell did the same.
Cresswell had a shot saved by Walker and then he hit the right hand post with a shot, before Lynch also hit the bar with a 15-yard header.