Quality control of red cell concentrates (RCC) was performed in six Blood Transfusion Centres in Croatia. Between 1.5 and 3.7% of the produced or/and used RCC were examined. Large differences in volume and haematocrit were found between red cell concentrates. 63.2% of concentrates had a volume larger than 225 ml. The mean haematocrit was 65.5%, and a haematocrit above 65% was observed in 51.6% of RCC. From 3.5% of RCC bacteria were isolated (gram positive coccus, Staphylococcus albus, Staphylococcus epidermidis and Streptococcus haemolyticus). The quality of RCC was not found to be satisfactory. In order to improve their quality procedures for their production, standards and legal requirements have to be established.