Hairballs can become a problem when you're living with seven cats!  For awhile it seemed like I was always cleaning up their icky hairball barf piles on the carpet.  I started using this food and it has nearly eliminated my hairball problems - has probably cut down on hairballs by 90% at least.  The cats love the food, and I know they are getting great nutrition from Science Diet.  My only gripe about the food is that I have several overweight cats and I had been feeding them Science Diet Light - if only they would make the Hairball Control in a Light version!!