The cross-national consistency and variation of gender differences in subjective health complaints was examined in a sample of 125732 11- to 15-year-olds from 29 European and North American countries, participating in the WHO collaborative study 'Health behaviour in school-aged children (HBSC) 1997/98'. Health complaints were measured with the Health Behaviour in School-aged Children Symptom Checklist. Gender differences in health complaints were analysed through multilevel logistic regression analysis. The results indicated a very robust pattern of increasing gender differences across age, with 15-year-old girls as a group at increased risk for health complaints across all countries. The magnitude of gender differences varied across countries, with some countries showing a consistently strong gender difference across age group and different health complaints, and other countries showing a consistently weak gender difference. The gender difference in health complaints was stronger in countries with a low gender development index score. The findings underscore the need to incorporate socio-contextual factors in the study of gender health inequalities during adolescence.