Objective: To examine the relation between household water and sanitation, and the risk of stunting and reversal of stunting in Khartoum and Crezira regions Sudan. Design: Prospective cohort study. Setting: A total of 25 483 children aged 6-72 months from rural Sudan enrolled in an 18-month field trial in 1988 to study the effect of vitamin A supplementation on child health and survival. Results: The mean height-for-age z-scores at baseline and the end of study were À1.66 and À1.55, respectively, for the group with water and sanitation facilities, and À2.03 and À1.94 for the group without water and sanitation, after adjustment for age, region, gender, mother's literacy, intervention group (vitamin A vs placebo), family wealth, breastfeeding and cleanliness. Among children of normal height-for-age at baseline, the risk of stunting (oÀ2 height-for-age z-score) was lowest in the group that came from homes that had both water and sanitation compared to children from homes without these facilities (multivariate RR ¼ 0.79, 95% CI 0.69-0.90). Among children stunted at baseline, those coming from homes with water and sanitation had a 17% greater chance of reversing stunting than those coming from homes without either facility (adjusted RR ¼ 1.17, 95% CI 0.99-1.38). We did not detect a synergistic association between access to water and sanitation. Conclusions: Water and sanitation are independently associated with improved growth of children. Sponsorship: None.