The aim of this study was to compare blood serum progesterone levels by using different progesterone radioimmunoassay kits, in different stages of sexual cycle and pregnancy in the cow (n=25), sheep (n=25) and bitch (n=25). Progesterone levels in blood serum samples of the materials were measured by human progesterone RIA kit (Immunotech (R)), bovine. ovine and canine progesterone RIA kit (Immunotech (R)) and a validated human RIA kit. Measurements were performed according to instructions of the kits. As a validation, standart interval was extended and standart points were set to 0, 2.5, 5 10, 20, 40 80 and 100 ng/ml of the human kit. There was no statistically important difference between the mean progesterone values obtained by using different test kits (p>0.05). The results were correlated at the level of r=0.999 and r=1.000 for cows; r=0.997 and r=1.000 for sheeps and r= 0.994 and 0.998 for bitches. In conclusion, human RIA and validated human RIA kits can be use safely instead of species specific test kits for the blood progesterone mesurements in the cows, ewes and bitches.