In response to Hurricane Mitch, which struck Central America in October–November 1998, the American Red Cross (ARC) and the Centers for Disease Control and Prevention (CDC) collaborated on a 3-year evaluation of the public health impact of ARC's water, sanitation and hygiene education activities in eight study areas in Honduras, Nicaragua, El Salvador and Guatemala. The evaluation compared: 1) access to and use of water and sanitation facilities, 2) the use of hygienic behaviours, and 3) diarrhoeal prevalence in children younger than 3 years of age before (February 2000) and after (February 2002) the interventions had been implemented. The evaluation included household and key informant interviews designed to measure these three components. Water quality of community water sources and household water was evaluated by measuring levels of indicator bacteria. During the final survey, an infrastructure evaluation provided a review of the design, construction, and current operation and maintenance of the water systems and latrines. The integrated water and sanitation infrastructure interventions and hygiene education programmes implemented following Hurricane Mitch effectively decreased diarrhoea prevalence in the target communities.