The current study was carried out to determine the prevalence of avian trichomoniasis in different species of pigeons in Mosul city during 2005-2007. In addition, the work aimed to investigate the effects of possible relationships between age, sex, season of the year, weight and health status on the incidence of the disease. Three species of pigeons were included viz, stock dove (Columba oenas), rock mountain dove (C. livia), and collared doves (Streptopelia decaocto).Examination of 250, 200 and 40 doves of the three fore–mentioned groups of birds indicated prevalence rates of 22%, 17.5% and 10%, for the three species, respectively. High infection rates were reported in squabs of all birds of the three groups. Regarding the effect of sex on the infection rate, the results revealed high percentage of infection were seen in male stock doves and female rock doves in comparison with their counterparts, however similar rates were observed in both sexes of collared doves. Also, it was found that there was an impact of season of the year on the prevalence rates of the parasite, so the infection was increased in spring and winter more than other seasons, for all birds studied. Depending upon our findings, factors such as body weight and health status have no effects on incidence of the disease.