Nine strains of tetraploid red clover obtained from forms producing of male and female gametes were studied. Tetraploids received from unreduced gametes appeared to be characterised by favourable parameters of seed yield structure traits. The yield of strains 4x was higher than that of colchiploids. Genetic variability obtained by crossing of forms producing unreduced male and fornale gametes resulted in better seed set increasing breeding and usability value of tetraploid red clover.