Bacteriological and virological examinations of Louisiana and Texas Gulf Coast oysters were done over a 12-month period. Oysters taken from approved waters sometimes contained detectable enteroviruses: echovirus 4 and poliovirus 1 were in one each of 17 samples from Texas, and poliovirus 3 was in one of 24 samples from Louisiana. Neither the coliform MPN for the water from the shellfish beds nor the coliform MPN, Escherichia coli MPN, or aerobic plate counts for the shellfish meats was clearly indicative of the presence of virus. Two of the 24 oyster meat samples which contatined Vibrio parahaemolyticus also yielded virus; however, virus was present in one of 17 samples in which V. parahaemolyticus was not detected. Poliovirus 1 was also found in frozen, shucked oysters imported from Japan.