Using RIA method, serum erythropoietin (EPO) levels were measured in 13 patients undergoing autologous bone marrow transplantation (ABMT) and 4 patients with autologous peripheral blood stem cell transplantation (APBSCT) before and at the end of conditioning regiment as well as at the 3rd, 7th, 10th, 14th, 20th i 30th day after ABMT in correlation with actual haemoglobin (Hb) value. Statistically significant increase in EPO level was observed at days 0 to +14 (p < 0.01) with the maximum at day 3. The correlation between increased EPO level and decreased Hb was observed.