Care of cancer patients may be a source of considerable stress. As part of a large scale longitudinal study of the interaction of biological, psychological and environmental factors in determining patient outcome, the mental and physical health status of 37 members of the nursing staff of a cancer hospital was examined. The study identifies risk factors for stress, professional 'burn-out' and psychiatric morbidity. An assessment questionnaire also examined work time, work organization, relationships with colleagues, identification of stressful situations, and treatment of pain. Each subject completed three scales designed to measure stress and psychiatric morbidity: the Nursing Stress Scale, the Maslasch Burnout Inventory and the General Health Questionnaire. Item analysis suggested that stress is primarily related to inadequate training, lack of time to deal with the psychological component of care giving especially terminal care, and relationship difficulties with other medical staff. Multiple analysis of correspondence indicated that in the face of stress, risk factors for professional burnout are high psychiatric symptomatology, lack of information at the time of diagnosis, poor perceived health, relationship difficulties with patients and their families, and work uncertainties.