The frequency and features of associated neoplastic diseases and their impact on survival were evaluated in a series of 232 patients with chronic lymphocytic leukemia (CLL) who had been diagnosed during an 18 year period. Thirty-two patients (13.8%) had overall 38 neoplasias, 27 of which were diagnosed after CLL. There were no significant differences in the initial clinical and hematological features of the patients depending on whether they had or not a second neoplastic disease or on the time of its development. When compared with the normal population of similar age and sex, the patients with CLL, particularly females, had and increased risk to develop other tumors. The actuarial analysis showed that the risk of developing associated tumors increased through time up to 36% nine years after the diagnosis (27% when skin neoplasias were excluded). Although differences in survival were not found between patients with CLL and associated tumor and the rest of the series, most patients with noncutaneous neoplasia died as a direct consequence of it 18 months after its diagnosis.