The new effective protocols of treatment of chronic B-cell lymphatic leukemia, including purine analogs and monoclonal antibodies, provide robust remissions under this disease. Accordingly, the requirements to remission quality assessment are changed too. In particular the assessment of minimal residual disease is obligatory. To assess minimal residual disease in terms of quantity in case of chronic B-cell lymphatic leukemia the technique of polymerase chain reaction was applied in real time with patient-specific primers from the area of V-D-J combinations of genes of heavy chain of immunoglobulin. The study included samples from 60 patients suffering of chronic B-cell lymphatic leukemia. In 15 of them (25%), it was impossible to apply neither the sequence analysis of genes of heavy chain of immunoglobulin nor the fitting of patient-specific primer. The results of quantitative determination of minimal residual disease were obtained in 45 patients (55 tests). The minimal residual disease was detected in 30 of 55 samples (54.5%) and was not detected in 25 of 55 samples (45.5%). At the same time, the quantitative determination of minimal residual disease was implemented in regard to the initial level of neoplastic cells. The method sensitivity qualified by serial dilutions, consisted 10(-5) or 1 neoplastic cell to 100 000 normal cells. The comparative analysis was applied to the results of determination of minimal residual disease using two methods -polymerase chain reaction in real time using patient-specified primers and four-color flow cytofluometry. The determination of minimal residual disease with both methods was implemented in 37 patients (45 tests). The results of both methods matched in 93.3% (42 tests out of 45) with maximal disparity of one degree. Then Spearman factor consisted 0.87 (p < 0.0001). In 3 out of 45 tests (6.7%) neoplastic cells were detected with only one method. In the first case, it was the method of four-color flow cytofluometry and in other two cases it was polymerase chain reaction in real time. Therefore, the detection of minimal residual disease under chronic B-cell lymphatic leukemia using the method of polymerase chain reaction in real time is rather sensitive and specific and correlates with the results received with the method of four-color flow cytofluometry. The results are the same in the case of using anti-CD20 monoclonal antibodies under treatment.