His father Falik (Felix) Catovsky was born in Vertiujeni, Floresti district. In 1930, Felix emigrated to Argentina. He was a journalist and editor of Buenos Aires magazines - "Our Life" and "Press". Daniel Catovsky was Honorary lecturer, Royal Postgraduate Medical School, London, 1971-1976; honorary senior lecturer hemato- logy, Royal Postgraduate Medical School, 1976-1987; professor hematology oncolo- gy, Royal Postgraduate Medical School, 1987-1988; professor hematology, Institute Cancer Research, London, since 1988. Honorary consultant Royal Marsden Hospital, London, since 1988. Faculty member European School Hematology, since 1990. Membership: Secretary advising committee Lady Tata Memorial Trust, since 1983. Fellow Royal College Pathologists (London), Royal College Physicians (London). Member British Society Hematology (president 1996-1997). Historically, an increase in the percentage and number of circulating pro- lymphocytes in chronic lymphocytic leukaemia (CLL) has been associated with strong expression of surface immunoglobulin, trisomy 12 and a poor outcome. This study re-examines the biological and clinical significance of increased peripheral blood pro- lymphocytes in 508 patients at entry into the randomized UK Leukemia Research Fund CLI4 trial. It also investigates the associations between increased prolympho- cytes and a comprehensive array of biomarkers.