Summary and Conclusions 1. In an attempt to develop a therapeutic regimen suited for rapid mass administration to unhospitalized ambulatory patients, Fuadin (“Repodral-Wintrop”) was employed in the treatment of 55 Syrian villagers known to be infected with S. haematobium. 2. Treatment was preceded by a complete physical examination including blood studies, examination of thorax and abdomen, blood pressure, temperature, and radial pulse measurements, and individuals showing organic or other complicating conditions other than urinary schistosomiasis were ruled out. The general physical condition of the villagers is discussed briefly. 3. The drug was administered intramuscularly over a three-day period to adults in a course of 34 cc. of a 6.3 per cent solution, comprising a total of nine injections. The first day, three injections of 2 cc., 4 cc., and 4 cc. were given at four-hour intervals. On the subsequent two days, three injections of 4 cc. each were given daily at three hour intervals. In school children, a total dose of 17 cc. was administered in nine injections given over a three day period. The first dose of 1 cc. was followed by two doses of 2 cc. each at three hour intervals, and the remaining six doses were given as three 2 cc. doses daily taken at three hour intervals. 4. Reaction to the drug was generally mild, although considerable muscular soreness developed in the buttocks, the site of injection. Transitory constitutional reactions developed in some of the cases, particularly among the adult group. In no case, was it felt that the toxic manifestations were severe enough to warrant discontinuance of the treatment. 5. Follow-up studies were made for a five-day period immediately after treatment, and repeated two weeks later. Effectiveness of treatment was judged by egg-hatching experiments, with particular attention to the percentage of cases showing: (1) free-swimming miracidia in diluted urine sediments, (2) unhatched, normal-sized eggs, (3) small, degenerate eggs and (4) no eggs. Later follow-up studies, while admittedly desirable, would have been complicated by constant opportunity for re-infection. 6. Because of the unavoidable brevity of the second follow-up study, it is not felt that any sweeping claims can be made concerning the intensive therapeutic regimen described herein. It is felt, however, that cessation of egg production in roughly 50 per cent of the cases during the last three days of the second observation period, and the complete cessation of production of free-swimming miracidia in from 60 to 70 per cent of the cases during the last four days of the second observation period, constitutes evidence of definite improvement. 7. Attention is called to the possible value of such an intensive short-course treatment as a prophylactic approach applicable to public health programs, where mass reduction in viability of eggs voided by man, the only suitable definitive host for this parasite, would prevent suitable snail hosts becoming infected, thus contributing heavily toward a reduction of the disease in endemic areas. 8. In view of the apparent lack of toxicity of Fuadin when given under the intensive regimen, its further trial and study under similar conditions seems indicated.