A group of 38 patients with a median age of 70 years and chronic lymphocytic leukemia (CLL) were treated using a cobalt 60 U or a 6‐MeV linear accelerator. A direct field or two opposite fields covered the palpable spleen area in most patients. 100 cGy were administered weekly for a total dose of 10 Gy, given over 10 weeks. The stage arrangement (according to Rai) for the 32 evaluable patients was as follows: Stage I: 11 patients, Stage II: nine patients, Stage III: three patients, and Stage IV: nine patients. Patients in Stages I and II were treated when symptomatic. Twenty‐five patients (78%) achieved hematologic response (HR), defined as normalization of the differential leukocyte count, of the total blood cell count, and of bone marrow infiltration. However, no complete response according to the standard criteria of response has been obtained. The median response time of HR was 7 months (range, 1.5 months to > 120 months). The overall median survival time from the start of splenic irradiation (SI) was 40 months. More than 50% splenomegaly reduction was obtained in 63% of patients, whereas no benefit was verified in the lymphadenopathy. The incidence of second tumor was 29%. Fourteen patients benefited from a further 21 SI cycles. SI does not result in a complete remission and threfore cannot modify the course of CLL. This treatment is most advisable for elderly patients with predominant bone marrow lymphocytosis, for patients with previous extensive chemotherapy or radiotherapy, and for patients with poor marrow reserve. Moreover, because of the absence of toxicity subsequent treatment is not compromised.