every three or four months, get a small tub with a towel on the bottom. fill the tub with warm water, not hot. put your guinea in the water and wash its hair with Johnson's baby shampoo or guinea pig shampoo. rinse soap out with warm water using a small container making sure you don't get water in their eyes or nose. take your guinea out and place on warm towel. pat him off and then comb his hair. don't put him back into the cage until he is nice and dry and warm.