Ninety-six previously untreated patients (67 males/29 females; mean age: 63 years; range: 46-84) with CLL in stage B (62 cases) or C (34 cases) were randomized to be treated with either chlorambucil (0.4 mg/kg orally days 5 and 6) plus prednisone (60 mg/m2 orally days 1 to 4) (CL + PDN) every 2 weeks or cyclophosphamide (160 mg/m2 orally days 1 to 4), melphalan (6 mg/m2 orally days 1 to 4), and prednisone (60 mg/m2 orally days 1 to 4) (CMP) every 3 weeks for 10 months. Forty-eight patients were treated with CLR + PDN, and the remaining 48 with CMP. The following types of response were considered: complete response (CR): total disappearance of symptoms and signs related to the disease. Partial response (PR): shift of the disease to a less advanced stage. Stable disease (SD) no change in the stage after treatment. Progressive disease (PD): progression of the disease to a more advanced stage. Thirty-six (75%) responses (27% CR) with CLR + PDN and 26 (54.5%, 12.5% CR) with CMP were observed (p = 0.054). Although more responses were achieved in stage B (69%, 24% CR) than in stage C (54%, 12% CR) this difference did not achieve statistical significance. Survival was statistically not different for those patients treated with LCR + PDN as compared to those receiving CMP.(ABSTRACT TRUNCATED AT 250 WORDS)