Infections are common in children attending daycare centres (DCCs). We evaluated the effect of a hand hygiene (HH) intervention for caregivers on the incidence of gastrointestinal and respiratory infections in children. The intervention was evaluated in a two-arm cluster randomized controlled trial. Thirty-six DCCs received the intervention including HH products, training sessions, and posters/stickers. Thirty-five control DCCs continued usual practice. Incidence of episodes of diarrhoea and the common cold in children was monitored by parents during 6 months. Using multilevel Poisson regression, incidence rate ratios (IRRs) with 95% confidence intervals (CIs) were obtained. Diarrhoeal incidence was monitored in 545 children for 91 937 days. During follow-up, the incidence was 3.0 episodes per child-year in intervention DCCs vs. 3.4 in control DCCs (IRR 0.90, 95% CI 0.73-1.11). Incidence of the common cold was monitored in 541 children for 91 373 days. During follow-up, the incidence was 8.2 episodes per child-year in intervention DCCs vs. 7.4 in control DCCs (IRR 1.07, 95% CI 0.97-1.19). In this study, no evidence for an effect of the intervention was demonstrated on the incidence of episodes of diarrhoea and the common cold. (author abstract)