AIMS: To use school nurses' knowledge and experience for a better understanding of schoolchildren's health problems and their association to socioeconomic background and gender. METHODS: Mail questionnaires were sent to a nationally representative, random sample of Swedish school nurses (n=129). The questionnaire included structured and open-ended questions asking for school nurses' judgement of schoolchildren's health status; changes over the previous two years; estimation of schoolchildren's most common reasons for consulting the school nurse; and estimation of factors influencing schoolchildren's health. RESULTS: Swedish school nurses judged schoolchildren's mental health to have deteriorated during the previous two years with increasing health complaints, especially among girls and in disadvantaged housing areas. Disturbed family relations were considered as one important explanatory factor. Girls were more inclined to consult school nurses with subjective health complaints. Boys more often consulted the nurses with physical injuries. CONCLUSIONS: School nurses work closely with the children and meet them continuously during the school age period. They have a genuine knowledge of schoolchildren's health, which should be used even more, both in research and practice. The results may be applicable in other countries with similarly organized school health systems.