The aim of our study was to determine the efficacy and toxicity of 2-chlorodeoxyadenosine (2-CdA) in 2-hour infusions in the treatment of elderly patients with B-cell chronic lymphocytic leukemia (B-CLL). Forty three patients aged 70 years and older received 1 to 6 courses of 2-CdA (median 3) in a dose of 0.12 mg/kg daily for 5 consecutive days. Thirty three of them were untreated and 10 had relapsed or refractory to disease after prior therapy with chlorambucil, COP and CHOP. Complete response (CR) was achieved in 13 (30.2%) and partial response (PR) in 17 (39.6%) patients, giving an overall response rate of 69.8%. The difference in overall response rate between both groups were not statistically significant (69.8% and 50%, respectively). The most frequent side effects of 2-CdA treatment were thrombocytopenia observed in 18 (41.9%) and infections in 7 (16.3%) patients. Drug related neutropenia was observed in 6 (13.9%) and allergic dermatitis in 2 patients. Six (13.9%) patients died, one because of drug related thrombocytopenia resulting in a central nervous system hemorrhage, two because of pneumonia and two of cardiovascular complications. In conclusion, our results suggest that 2-CdA is also effective treatment for elderly patients with CLL. The drug toxicity is acceptable and seems to be similar for that observed in younger patients.