BACKGROUNDThe potential of insecticide-treated bednets (ITNs) to contribute to child survival has been well documented in randomised controlled trials. ITN coverage has increased rapidly in Kenya from 7% in 2004 to 67% in 2006. We aimed to assess the extent to which this investment has led to improvements in child survival.METHODSA dynamic cohort of about 3500 children aged 1-59 months were enumerated three times at yearly intervals in 72 rural clusters located in four districts of Kenya. The effect of ITN use on mortality was assessed with Poisson regression to take account of potential effect-modifying and confounding covariates.FINDINGS100 children died over 2 years. Overall mortality rates were much the same in the first and second years of the study (14.5 per 1000 person-years in the first year and 15.4 per 1000 person-years in the second). After adjustment for age, time period, and a number of other possible confounding variables, ITN use was associated with a 44% reduction in mortality (mortality rate ratio 0.56, 95% CI 0.33-0.96; p=0.04). This level of protection corresponds to about seven deaths averted for every 1000 ITNs distributed.INTERPRETATIONA combined approach of social marketing followed by mass free distribution of ITNs translated into child survival effects that are comparable with those seen in previous randomised controlled trials.