Survival experience of 398 patients with chronic lymphocytic leukemia (CLL) seen at the University of Kansas Medical Center between 1942 and 1968 was computed by a standard actuarial method. Median survival for all patients was 4.5 years. Of the 398 patients 40 had never received any treatment for their CLL. The untreated patients were older at diagnosis than the treated patients (67.0 vs 61.5 years) and lived longer (6.0 vs 4.5 years median survival). Thus, there is a distinct group of older patients with CLL whose disease is usually diagnosed accidentally, who do not require treatment for their CLL, and who tend to live longer than average treated CLL patients.