Because of public health concerns, regulators are considering requiring post-harvest treatment of halfshell and shucked oysters by wholesalers and processors. Two recently developed post-harvest treatment technologies may actually reduce the costs of producing shucked oysters, but would increase the costs of halfshell oysters. An interregional model of the wholesale oyster industry is developed to estimate the effects of treatment requirements on prices, output, and employment. If post-harvest treatment is required for all Gulf oysters, price increases are estimated to be less than 20% and, in some cases, prices decrease. Results indicate producer and consumer losses in the halfshell market are partially or more than offset by gains in the shucked market.