Antimicrobial drugs are frequently fed to hogs at sub-therapeutic levels to promote feed efficiency and growth. However, in response to concerns that sub-therapeutic antibiotics (STAs) are promoting the development of antimicrobial drug-resistant bacteria, the U.S. Food and Drug Administration recently adopted a strategy to phase out antibiotics for such “production uses.” This study uses a stochastic frontier model to estimate the costs to U.S. hog producers of a ban on STAs for growth promotion. To address potential sample selection issues, we employ a recently developed empirical approach that corrects for biases from both observed and unobserved variables.