Arylsulfatase A and B in urine have been estimated in 18 normal subjects and 50 bilharziasis patients. The bilharziasis patients were divided into two groups according to the type of infeciton. Those with bilharziasis haematobian type of infection and those with the bilharziasis mansoni type. Each group was further subdivided into subgroups according to the severity and progress of the disease. The activities of arylsulfatase A and B were significantly elevated in all the groups of patients studied and it is evident that there is a progressive increase with the progress of the disease in both types of bilharziasis infections (the haematobian and mansoni types). Liver dysfunction consequent of bilharzial infestation appears to take part in the mechanism of induction of the bilharzial bladder cancer.