The authors present clinical analysis of 57 patients with chronic lymphocytic leukaemia, observed during the first three stages of the disease according to Rai classification. The analysis of the presented material has confirmed the clinical and prognostic value of this classification, but at the same time has shown differences of clinical course of the disease in particular patient. There was no sex neither age effect on the clinical course of chronic lymphocytic leukemia. The authors confirmed that leukocyte doubling time is a very useful prognostic factor in chronic lymphocytic leukaemia.