The World Health Organization's International Code of Marketing of Breast-Milk Substitutes, as well as most major medical authorities, opposes hospital-based distribution of free infant formula at discharge. The goal of this cross-sectional telephone survey of 3209 US maternity sites, conducted from 2006 to 2007, was to determine the extent of this practice. It was found that 91% of hospitals distributed formula sample packs, and a trend toward discontinuation of the practice was statistically significant (P < .001). It was concluded that most US hospitals distribute infant formula samples, in violation of the WHO Code and the recommendations of organizations including the US Government Accountability Office, the American Academy of Pediatrics, and the Centers for Disease Control and Prevention.