The possible economic impacts of proposed restrictions on the subtherapeutic level use of penicillin and tetracyclines and a proposed ban on use of nitrofurans in poultry rations were estimated for layers, broilers and turkeys. The 1976 production year was used as the base period. Changes in output levels and production costs associated with changes in production performance accompanying the restrictions were estimated. Two scenarios were evaluated: one in which it was assumed that the breeder flock size was held constant and final output was reduced and one in which there was a buildup in the breeder flock size and the level of final output remained the same. The results indicate that each of the proposed restrictions would result in higher costs per unit of poultry produced and probably less total output. If previous base period output levels were continued after the restrictions were imposed, average production costs could increase as much as 1.5 cents per dozen for eggs, 2.0 cents per pound RTC for broiler meat and 1.5 cents per pound RTC for turkey meat. Total costs of U.S. poultry production could increase as much as $281.5 million. If previous base period breeding flock sizes were maintained, poultry industry output could decrease as much as 350 million dozens of eggs, 1.1 billion pounds RTC broiler meat and 174 million pounds RTC turkey meat. Total production costs, however, could also decrease as much as $269.1 million.