Eight cases of follicular lymphoma of the spleen were found among 863 spleens surgically removed from patients with hepatosplenic schistosomiasis mansoni (0.9%). Superficial lymph nodes were not enlarged. A supraclavicular mass developed in one patient 3 months after splenectomy that was proved histologically to be a reticulosarcoma. Another patient died 2 months after surgery; no changes attributable to follicular lymphoma were found at necropsy. All patients had huge spleens that had on the cut surface numerous whitish nodules varying in diameter from 0.1 to 0.6 cm. Since follicular lymphoma is the least frequent type of lymphoma and its isolated splenic form is an extraordinary rarity, the occurrence of eight cases of this condition associated with hepatosplenic schistosomiasis was not considered merely coincidental. We suggest that the changes in the spleen caused by advanced schistosomiasis, which include cycles of follicular hyperplasia and involution, predispose this organ to the development of follicular lymphoma in some patients.