The expression of Bcl-2, P53 proteins and known markers of proliferation, namely proliferating cell nuclear antigen (PCNA) and Ki67, in 29 patients with B-cell chronic lymphocytic leukaemia (B-CLL) was investigated. All leukaemic patients were classified, and immunophenotyped by the two-colour immunofluorescence method with the use of fluorocytometry. B-CLL was heterogeneous in the range of biological parameters of tumour cells. B-CLL patients manifested 34% positive Ki67 and 61% PCNA expression, whereas Bcl-2 and P53 positivity was 81% and 42%, respectively. The level of intracellular expression of Bcl-2 and P53 proteins did not depend on the stage of disease estimated by routine methods. Ki67 and PCNA expression was significantly higher in B-CLL patients with more advanced stages of the disease. A statistically significant correlation was established between their mutual expression.