An epizootic of trichomoniasis in mourning doves at the Carolina Sandhills National Wildlife Refuge began in 1969 and continued into 1970. The disease was seen in 16% of the adults and 2% of the immatures in 1970, but only one immature bird out of 37 surveyed (3%) carried Trichomonas gallinae. Challenge infection of 33 doves from the epizootic area showed 85 percent to be resistant to trichomoniasis, compared to 69 percent resistance in doves from Maryland, where no epizootic has occurred for at least 3 years. Plasma protein changes which occurred following challenge infection were identical in CSNWR and Maryland doves which showed evidence of disease. Of the doves which showed no signs of disease, those from the CSNWR exhibited no change in beta globulins, identical to the response in pigeons which survive an infection by T. gallinae, but they had some tissue invasion by the parasite.