Abstract: Objective Diarrheal and respiratory diseases cause millions of deaths among children in the developing world each year.Studies demonstrated reduced rates of these diseases during intensive,ho me-based handw ashing interventions.To evaluate the effect of a schoo-l based handw ashinng progr am among 1st gr ade students to determine whether a more scalable,lowe-rcost interv ention could also affectillness rates.Methods Thirty schools from each of 3 counties in Fujian province,were randomized to one of the following groups:control;standard intervention,which included a handwashing program(1 hour of hygiene instruction and l soapsample kit perpupil);expanded intervention,which included the handwashing program and a supply of soapfor the school sinks.Teachers collected illness symptom information from students weekly and student absences daily between January and A pril,2005.Mean illness and absence rates were calculated for each school and were compar ed across groups.Wilcoxon ranksums were perfo rmed and p values <0.05 significant was considered.Results There were a total of 52 342 studen-tweeks of observation.In control schools,children experienced a median 2.04 episodes of absence(median 2.58 days of absence)per 100 studen-tweeks.In standard intervention schools,there were a median 1.15 episodes of absence(median 1.86 days of absence)per 100 studen-tweeks.Children in ex panded intervent ion schools experienced a median 1.19 episodes of absence(median 11.9 days of absence)per 100 student-weeks.T he control and ex panded intervention g roups differed sig nificantly in occurr ence of illness absence(P=0.03)and in number of days absent(P=0.02).Conclusion Provision of hand washing promotion program and soap was signig nicantly associated with reduction in illness,absence and days of absence among 1 st grade students in Fujian province.This low-cost,lar ge-scale intervention could improve the health of children world wide.