SummaryThis study reviews the relationship between the health and behaviour of 870 preschool children reviewed over a 5‐year period. Detailed information was collected at regular intervals on rates of upper and lower respiratory tract infections, ear infections, and other illnesses. The children were examined, and their behaviour was assessed using questionnaires. In addition, the mothers of the children were interviewed, and assessment was made of levels of maternal stress. Relationships are demonstrated between episodes of illness and different behaviour problems. Night waking, poor appetite, temper tantrums, difficulty in management, and the doctor's and mother's overall assessment of behaviour were all found to be correlated with recurrent minor illnesses. Relationships were also found between maternal stress and some of the behaviour variables. Attention is drawn to the well known association of stress with physical illness, and the importance of this relationship in the management of both infections and behaviour problems in the young child is discusse