We undertook this study to characterize the haematological indices in centenarian subjects who should be an excellent group to study the mechanisms of physiological aging. This study is a part of the Polish Centenarians Program co-ordinated by the International Institute of Molecular and Cell Biology in Warsaw. We examined 89 subjects aged 100 to 111 (14 males and 75 females). Mean values of all haematological parameters were within the normal range in females. In males, haemoglobin level (Hb), red blood cell count (RBC) and hematocrit (Hct) were slightly lower than WHO references (12.7 +/- 1.3 g/dl, 4.10 +/- 0.48 M/ml and 38.4 +/- 3.8%, respectively). However, anaemia was more frequent in females than in males (57.1% vs 29.1%, p < 0.05). In females with anaemia there was a tendency to decrease its severity with age. In the oldest group (aged 105-111 years) Hb and Hct had a tendency for lower values vs the youngest group (100-101 years) (10.1 +/- 1.8 g/dl vs 11.6 +/- 0.1 g/dl, p = 0.067 and 30.9 +/- 5.0% vs 35.0 +/- 0.3%, p = 0.067). Additionally, in the youngest group there were three females with severe anaemia (Hb < 9.0 g/dl) whereas in the oldest group all females with anaemia had Hb above 11.0 g/dl. In males the analysis was not undertaken because of small group of studied subjects. In conclusion, anaemia seems to be a relatively common problem in studied centenarians. Severe anaemia seems to be an eliminating factor in centenarian women.