The modal volume of peripheral blood lymphocytes from 23 patients with chronic lymphoid leukemia (CLL) was measured by a Coulter ZBI linked to a channalyzer C 1000, varied from 140 to 262 mu3. A statistical correlation between the modal volume and anatomo-clinical forms of the disease was determined: a modal volume below 190 mu3 was statistically found among early forms while a volume over this threshold corresponded to advanced forms. Since Sipe et al. postulated that cell volume might be relayed to the cell kinetics, we attempted to determine the volume distribution law of lymphocytes from 12 CLL cases by applying the chi-square distance test. The best adjustment was observed with the two log-normal populations model, but this adjustment was acceptable for only five cases over twelve. The instability in the determination of the percentage of the second population made it impossible + relate it with the proliferative cell fraction. Moreover, this model did not provide more significant information than the single modal volume.