In the course of a successful collaboration between the Centers for Disease Control and Prevention (CDC) and the cruise ship industry on reducing common-source outbreaks, CDC's Vessel Sanitation Program (VSP) has expanded its training, education, and cruise ship inspection programs. The study reported here evaluated 15 years of ship sanitation inspection data from the National Center for Environmental Health and assessed performance in specific sanitation categories from 1996 to 2005. During the period 1990-2005, scores from cruise ship environmental sanitation inspections steadily improved. The percentage of inspections with violations decreased among five of nine categories. Those five categories were Washing Facilities, Contact Surfaces, Facility Maintenance, Food Handling, and Communicable Disease Practices. Inspection violations increased proportionally in the categories of Swimming Pools and Water System Protection/Chart Recording. Overall continued good performance in most sanitation categories is likely attributable to on-site training during inspections, improvements in ship construction, and a switch from hot-holding temperatures to time limits as a public health control for foods on display.