The study presents results of B and T lymphocytes population analysis in patients with chronic lymphocytic leukaemia B cells and autoimmune haemolytic anaemia (CLL-B + AIHA). We evaluated the following groups of patients: (1) with newly recognized CLL-B and co-existent AIHA (untreated), (2) after short-term treatment with corticosteroids, (3) after treatment with chemotherapy and corticosteroids. The control groups were made of patients with CLL-B without AIHA. The populations of lymphocytes and determination of cells immunophenotype were performed by means of flow cytometry. The analysed data were obtained from 25 patients. The untreated patients with CLL-B + AIHA presented significantly more numerous population of neoplastic cells CD19+ CD5+ in comparison with patients without AIHA. The patients with AIHA showed a reduced percentage of B CD19+ CD22+ cells in comparison with those without AIHA. Untreated patients with AIHA or after a short-term corticosteroid treatment showed a higher ratio of the number of CD19+ CD5+ cells to the number of T CD4+ and T CD8+ lymphocytes than CLL-B patients without AIHA. It can be presumed that the differences found may be related to the pathogenesis of the autoimmune haemolysis syndrome in patients with CLL-B.