Public health experts are concerned about the diminishing efficacy of antibiotics. Some have called for a ban on growth-promoting antibiotics in animal agriculture. This study identifies the contribution of growth-promoting antibiotics in the grower/finisher phase of U.S. pork production. With National Animal Health Monitoring System swine data, relationships are estimated between growth-promoting antibiotic use and productivity. Results indicate improvements in average daily gain (0.5%), feed conversion ratio (1.1%), and mortality rate (reduced 0.22 percentage points); these productivity improvements translate into a profitability gain of $0.59 per pig marketed, or an improvement of 9% in net profits associated with growth promotion antibiotics.