BACKGROUND: The planning of child mental health services should be based on recent high-quality data on the prevalence and type of mental health disorders, and yet such data are not available in Yemen and many other Arab countries. METHODS: Representative samples of Yemeni 7-10 year olds (n = 1,210) were assessed using a two-phase design in an urban area and a one-phase design in a rural area. Psychopathology was assessed using the Strengths and Difficulties Questionnaire for screening purposes and the Development and Well-being Assessment to generate psychiatric diagnoses. RESULTS: The overall prevalence of DSM-IV disorders was 15.7% in Yemen (95% CI 11.7-20.2%). Anxiety disorders were the commonest diagnostic grouping in Yemen (9.3%, 95% CI = 5.8-12.8%), followed by behavioural disorders (7.1%, 95% CI = 4.4-9.9%) and attention-deficit/hyperactivity disorder (ADHD; 1.3%, 95% CI = 0.1-2.5%). There were no significant urban-rural differences. CONCLUSIONS: Roughly a sixth of Yemeni schoolchildren have at least one DSM-IV psychiatric disorder, involving a level of distress or social impairment likely to warrant treatment.