Eleven patients with malignant lymphoma had sperm counts done in the course of maintenance treatment with the alkylating agents chlorambucil or cyclophosphamide. Of the nine patients treated with chlorambucil, all had aspermia after treatment with doses ranging from 10.1 to 17.7 mg/kg of body weight. The two patients treated with cyclophosphamide had aspermia after a total dose of 227 and 980 mg/kg. One patient has been observed for one year following the cessation of alkylating agents and no return of spermatogenesis has occurred. Three patients had had radiation therapy to portals below the diaphragm and in these cases scatter irradiation might have been a contributing factor.