Sixty-one consecutive patients with chronic lymphocytic leukemia (CLL) treated at the Istituto Nazionale Tumori of Milan from September 1962 to August 1976 were classified according to the staging system of Rai et al. (16). Analysis of this series showed the following median survival (in months) from diagnosis: stage 0-I, 73; stage II, 44; stage III-IV, 32. In 11 patients without peripheral palpable adenopathies, the lymphangiogram showed abnormal retroperitoneal lymph nodes. Therefore, the initial stage was changed from 0 to I in 5 cases. The median survival for the entire series was 50 months. Patients with "indolent" disease had a median survival of 52 months, while in patients with "active" CLL, the median survival was 32 months. Both sex and age were shown to be poor predictors of survival. Increased duration of survival was observed in patients with less compared to those with more than 30,000 lymphocytes/mm3 (66 versus 41 months). The method of staging proposed by Rai et al. and utilized to classify this series at the time of diagnosis was confirmed to be a reliable predictor for survival.