Lack of adequate sanitation, hygiene and safe portable water are serious global health problems that contribute to deaths of many children under the age of 5 years annually, mainly due to diarrhoeal diseases. This study was set out to determine the extent to which sanitation and hygiene promotion influenced mothers' and children's health in Turkana District; one of the arid Northern frontier Districts of Kenya. A repeat cross-sectional study design with multi-stage sampling method was used. A total of 300 mothers were randomly sampled for interviews in a baseline survey carried out in 2007 and in a post-intervention survey carried out in 2008. Data were collected using questionnaires and analyzed using SPSS for frequencies, cross tabulations and regression amongst other tests. Significant improvements were observed in hand washing practice, presence of hand washing soap at household and refuse pit ownership. In Kakuma Division the proportion of those who washed hands regularly increased from 48.8 to 91.3 % (χ(2) = 7.28, P = 0.122), in Lodwar Central, those who wash hands regularly increased from 85.5 to 89.9 % (χ² = 10.85, P = 0.028) while in Lokichogio, the proportions increased from 77.5 to 93.8 % (χ² = 15.56, P = 0.004). For hand washing soap at household, there was an increase in proportion of those who wash hands with soap from 65 to 78 % (χ² = 3.87, P = 0.049) within the group with no formal education. There was significant reduction of diarrhoea prevalence in children aged less than 5 years. Sanitation and hygiene promotion based on community participatory approaches can lead to significant reduction of diarrhoea in children.