Island endemic avifaunas face many threats, including the now well-documented impacts of pathogens. The impacts of pathogens on the endemic Seychelles avifauna, however, have been little studied. The protozoan parasite Trichomonas gallinae has been shown to reduce survival and reproductive success of the endemic Pink Pigeon Columba mayeri on the nearby island of Mauritius. I investigated trichomonad infection prevalence and pathogenicity in endemic Seychelles Blue Pigeons, Alectroenas pulcherrima, and two introduced species of columbid, the Madagascar Turtle-dove, Streptopelia picturata, and the Barred Ground Dove, Geopelia striata, on the Seychelles island of Mahé during September-October 2007. I asked whether: 1) trichomonad infections occur in these species; 2) prevalence varies among species; and 3) birds show any signs of pathogenicity consistent with tricho-monosis. I use the results to assess the potential threat of this pathogen to A. pulcherrima. All three species were infected with trichomonads, and the overall prevalence was 27.5%. Alectroenas pulcherrima had higher prevalence (47.1%) than the two introduced species combined (24.3%). No infected individuals showed any signs of disease. These findings suggest that trichomonad parasites should be considered as a potential disease threat to the A. pulcherrima population.