The goal of this experiment was to determine the effect of male-male competition on broiler breeder mating strategies and reproductive success and to identify behavioral and morphological traits associated with high fertility. Males were kept in groups with no competition (one male and 10 females; 1M), or high male-male competition (three males and 10 females; 3M). For each male we recorded the frequency of matings, forced matings, cloacal contacts and morphological traits (body weight, comb, wattle, tarsus and spur size), together with sperm quality and the reproductive success. Mating frequency consistently increased towards the end of the light phase. Significantly, higher mating activity occurred in 1 M groups compared to 3M groups. Mating frequency of 1M males, however, did not differ from the frequencies of the males with the highest mating frequency in 3M groups. After reducing the number of males from 3M to 1M in the second experimental phase we found significant increase in the mating frequency. This probably was a consequence of the reduction in the level of male-male competition or due to female response to a lower number of males. DNA fingerprinting results indicated that the males with the highest mating frequency did not always sire the most offspring within the group. The males with the highest sperm mobility or largest ejaculate volumes were equally successful. Frequency of forced mating was not affected by the level of competition, but was more likely used by heavier males or those with larger combs and wattles. We did not find any of the studied morphological traits to be reliable indicators of males reproductive potential, although this lack of association may have been affected by relatively low number of males available for this study.