It was tried to evaluate a quality of semen of merino rams in one year cycle in which 4 examination periods were distinguished. The examinations periods were shifted by about 42 days comparing with seasons (time of spermatogenesis and movement of spermatozoons via the reproductive tract of rams). Every week from each of 6 rams two ejaculates were examined including biochemical analysis (a content of fructose and activity of AspAT). It was found that quality of semen increased along with a shortening of days and that maximal values of all semen parameters were noted in November-January. The highest activity of AspAT was noted from February to April and the highest content of fructose in semen was found in May-July.