In this study early pregnancy diagnosis rate was determined in ewes that previously synchronised by MAP, PMSG and GnRH and bred naturally in late anestrous season.

Fourty Merino ewes, 5 years old, were used as materials. Jugular blood samples were collected on 15 th, 16 th and 17 th days, after breedings. Samples were santrifuged in 2000 rpm and plasmas were stored at —20 °C until assay procedures.

For the early pregnancy diagnosis, plasma progesterone and oestradiol 17 β levels were determined by RIA method. For this purpose, Mini assay type Gamma counter and 1251 Progesterone and Oestradiol 17 (3 assay kits were used. Laboratory results were controlled with lambing results.

As a conclusion, the high rate of correct diagnosis were obtained in pregnant and nonpregnant ewes, 84.62 % and 85.72 % respectively. While progesterone values were useful for early diagnosis, oestradiol values were not clear enough to decide the diagnosis.