Previous research suggests that social workers experience high levels of stress and burnout but most remain committed to their work. To examine the prevalence of stress and burnout, and job satisfaction among mental health social workers (MHSWs) and the factors responsible for this. A postal survey incorporating the General Health Questionnaire, Maslach Burnout Inventory, Karasek Job Content Questionnaire and a job satisfaction measure was sent to 610 MHSWs in England and Wales. Eligible respondents (n=237) reported high levels of stress and emotional exhaustion and low levels of job satisfaction; 111 (47%) showed significant symptomatology and distress, which is twice the level reported by similar surveys of psychiatrists. Feeling undervalued at work, excessive job demands, limited latitude in decision-making, and unhappiness about the place of MHSWs in modern services contributed to the poor job satisfaction and most aspects of burnout. Those who had approved social worker status had greater dissatisfaction. Stress may exacerbate recruitment and retention problems. Employers must recognise the demands placed upon MHSWs and value their contribution to mental health services.