Some haematological variables including Red Blood Cells (RBC), White Blood Cells (WBC) differential counts, Haemoglobin (Hb), Haematorite (HCT), Mean Corpuscular Volume (MCV), Mean Corpuscular Haemoglobin (MCH) and Mean Corpuscular Haemoglobin Concentration (MCHC) were measured in 90 stellate sturgeon juveniles Acipenser stellatus (1-2 years old) and 90 Persian sturgeons Acipenser persicus (1-2 years old) at different water temperature 10-15C, 16-20?C and 21-25C. Also these parameters were evaluated in 84 adult including A. persicus (54 samples) and A. stellatus (30 samples) collected from Caspian Sea during spring and autumn 1997. The results have showed that WBC differential counts, Hb, HCT, MCV and MCH were identical for both species at the mentioned water temperatures. However, the values for RBC of A. persicus were generally less than those of A. stellatus. These haematological factors relatively increased with the water temperature increasing. Although RBC and WBC values of A. persicus were less than those of A. stellatus. The rates for HCT, MCV and MCH were higher in A. persicus.