Random samples of 95 pigeon squabs, 87 youngsters and 106 adult living pigeons were collected from different sources in Assiut province including domestic and racing pigeons of both individually housed and lofts pigeons. Examination of crop samples directly under microscope and cultural trial on artificial media revealed that the infestation with trichomonas gallinae was 24.2% in pigeon squabs, 40.2% in youngsters and 57.5% in adult pigeons. The clinical signs and post mortem lesions of naturally infested pigeon squabs, youngsters and adult pigeons were studied. Experimental transmission of the disease to pigeon squabs by feeding of the cultured trichomonads showed that all of the squabs became infested. The result of in vitro sensitivity test revealed that the parasite was very sensitive (100%) to both Flagyl and Fasigyn but less sensitive to acriflavin (25%). The in vivo sensitivity test showed that both Flagyl and Fasigyn were of high efficacy in treatment of all squabs experimentally infested with Trichomonas gallinae, while acriflavin was of low therapeutic effect.