The data were obtained from an end line survey conducted in 16 public primary schools in Tanzania, 12 months after introduction of a hand hygiene intervention. After the annual mass drug administration targeting helminth (worm) infections in school children, we randomized eight schools to an intervention comprising teacher-led classroom teaching, parental engagement sessions, environmental modifications and improved handwashing stations while the remaining eight school in the control arm continued receiving routine health education. We targeted to collect data from 200 children in each school and we also conducted a sub-study on hand contamination involving approximately 40 children in each school. We hypothesised that the intervention would have an impact on the prevalence of soil transmitted helminth infections assessed using the combined prevalence of Ascaris and trichuris infections. We also assessed the intervention effect on the prevalence of individual worm infections i.e. prevalence of ascaris and then prevalence of trichuris. Apart from the intervention effect on worm infections we also assessed whether the intervention would impact on reported handwashing behaviour at school and home. We  obtained adjusted intervention effects by adjusting for school level variables that showed imbalance at baseline for example ascaris infection prevalence, and access to piped water. In the hand contamination sub-study we hypothesised that the intervention would impact on the prevalence  of hand contamination with bacterial load and worm eggs.