Success of the embryo transfer programs is affected by many factors (breed, type, season, treatment). We assume, that periferical blood level of some metabolic hormones (IGF-1, thyroid hormones, leptin, insulin) affects the success of superovulation and ET. According to our results, there is a significant difference between the in and out of season periferial blood level of IGF-1 and insulin. Furthermore, decrease in the periferic blood levels of IGF-1 and insulin is less drastic in the pregnant recipients.