It depends on how many inches it is being lowered, I would say 1" is ok but 2"+ you'd better get a camber kit. I've noticed that some cars will only have either the front or back that needs a camber kit (lowered quite a bit for example my CRX needed a front but not a back, & on a buddies 99 Civic the rear camber was worst than the front.

Just get the camber kit, & make sure you get an alignment afterwards to make sure everything is "straight".