Four groups of specific pathogen-free, day-old chicks were infected experimentally with an avian arthrotropic reovirus strain R2 by four different routes:--oral, subcutaneous, foot-pad and intra-articular. These groups were followed sequentially to study: pathological changes in the hock joints and liver; cloacal virus shedding and the presence of virus in hock joints; serological responses as determined by enzyme linked immunosorbent assay (ELISA), agar gel precipitation (AGP) and virus neutralization tests. All 4 infected groups developed arthritis or tenosynovitis with synovial hyperplasia and lymphocytic infiltration. Foot-pad and intra-articular routes of infection were found to advance the disease process by 2 to 3 weeks after infection by these routes were associated with superficial degenerative changes in articular cartilage. Antibodies were detected at 2 to 3 weeks p.i. by all 3 methods, but there were no significant differences between the patterns of serological response in the infected groups. Injection into the foot-pad appears to be the most convenient and effective parenteral route of experimental infection.