Avian reoviruses (ARVs) can result in disease and economic losses in the poultry industry. Vaccines against ARV may not provide full protection and can cause adverse reactions. The coding sequence of the sigma C protein from strain S1133 of avian reovirus was expressed in Schizasaccharomyces pombe. Sigma C protein expression was demonstrated by Western blotting, and the protein was evaluated for its ability to protect specific-pathogen-free (SPF) chickens against challenge with the virulent S1133 strain. Serologic and challenge-infection data showed the efficacy of the recombinant vaccine administered orally each week for 3 consecutive wk. Sigma C protein induced antibody, as determined by enzyme-linked immunosorbent assay. Percentage (%) protection induced by the low dose (125 microg purified yeast-expressed sigma C protein/chicken) or the high dose (250 microg purified yeast-expressed sigma C protein/chicken) was 64 and 91, respectively. The commercial vaccine administered once or twice provided 82% protection. Results supported the feasibility of a plant-derived vaccine for use in poultry immunization schemes.