The average number of surgical cases of hydatid disease per year among Lebanese during 1949 to 1959 was 63. The case rate was 3.82 per 100,000 population per year. The heaviest concentration of cases was in Beirut and environs. Case rates were much higher among Christians (5.00) than among Moslems (2.24) and among Armenians (8.18) than among the general population. Age specific rates for age at operation for patients from Beirut showed that operations were performed with equal frequency among individuals 20 to 60 years of age. An unusually high percentage of infected males were shoemakers.