This study was carried out to evaluate the relation among progesterone (P4) concentration, number and diameter of corpora lutea, with pregnancy in three ewe breeds. Total of 61 ewes (25 Rahmani,  11 Romanov and 25 crossbred, Rahmani x Romanov) were ultrasonographic examined after natural mating up to 21 days to determined number and diameter of corpora lutea. Blood samples were collected from 8 ewes per group (4 pregnant and 4 non-pregnant) prior to ultrasound scanning to assay P4 concentration. Results revealed that, average of CLs diameter and P4 concentration were the highest (P<0.05) in of Romonov (8.04 mm and 4.41 ng/ml), but were insignificantly higher in crossbred (7.48 mm and 3.5 ng/ml) than in Rahmani (5.52 mm and 3.43 ng/ml). Mean number of CL was not affected significantly by ewe breed. Mean number and diameter of CLs and P4 concentration were the higher (P<0.01) in pregnant than in non–pregnant ewes. The interaction between ewe breed and pregnancy status on all traits was not significant. A positive significant correlation was found between each of number and diameter (mm) of CLs and serum P4 concentrations was recorded.  Conclusion, results of this study indicated that the differences in progesterone concentration among ewe breeds are in relation with pregnancy status, depending on number and diameter of corpora lutea.