 School absenteeism due to respiratory infections is one of the greatest problems in schools. Its high incidence and easy transmission among pupils have a great impact requiring a vast number of medical visits, hospitalisations, use of antibiotic and antipyretic treatments, symptomatic medication, etc. besides being a cause for school absenteeism and time off work for parents. Hand- washing is the most important and effective measure to prevent the transmission of infections. The investigators evaluated the effectiveness of a hand-washing programme using hand sanitizer in the prevention of school absenteeism due to upper respiratory infections. 