A rotavirus isolated from the intestinal contents of commercial ring-neck pheasant chicks was determined to be a group D rotavirus based on its RNA electropherotype and its serologic relatedness to known turkey group A and D rotaviruses using immune electron microscopy and agar-gel immunodiffusion assays. Further characterization revealed a buoyant density in cesium chloride of 1.347 g/cm3 for double-shelled particles and 1.365 g/cm3 for single-shelled particles. The average size for the pheasant-origin group D rotavirus was determined to be 80 nm for double-shelled particles and 70 nm for single-shelled particles. In contrast, the average size for a turkey group A rotavirus isolate was determined to be 73 nm for double-shelled particles and 60 nm for single-shelled particles. There was no evidence of viral replication by the pheasant-origin group D rotavirus (either cytopathic effect or increase in numbers of viral particles) after six passages in MA104 cells. The hemagglutinating activity of the pheasant origin group D rotavirus was compared with that of a turkey origin group A rotavirus. Differences and similarities were noted depending upon the species of erythrocytes employed and the temperature of incubation.