We present a case of a female patient (79 years) with pathohistologic diagnosis of Hodgkin's lymphoma (HL) (stage IIIB, histologic type MC) for which she was treated with chemotherapy according to LVPP protocol (6 cycles) with good therapeutic response. Unexpectedly, 18 months after HL diagnosis leukocytosis occurred (19.4 x 10(9)/L) with 65% of lymphocytes with lymphoplasmocytic differentiation. Immunophenotype of these cells is typical for B-chronic lymphocytic leukemia (B-CLL) (CD5/CD19+, CD23-, CD38 +/-; with weak expression of monoclonal light chains lambda). Molecular analysis confirmed clonal immunoglobulin heavy chain gene (IgH) rearrangement of peripheral blood lymphocytes. The diagnosis of B-CLL imposed the question of the connection between two neoplasms of lymphocytic origin. Molecular analysis of lymph node biopsy taken at the time of lymphoma diagnosis revealed clonal population of B lymphocytes. That test undeniably proved coexistence of both diseases from the beginning. The latest PCR analysis of archive peripheral blood smears confirmed B lymphocyte clonality without diagnostic criteria for lymphoproliferative disease of CLL type. This finding etiologically excludes secondary leukemia. The possibility of untypical presentation of CLL in transformation to Richter's syndrome with morphologic characteristics of HL from the beginning stays unconfirmed. The hypothetical question that remains unanswered is: "Was it one disease in different clinical forms?"