The association between psychosocial stress and susceptibility to upper respiratory tract infection was investigated in 45 children with a history of recurrent colds and flu, and in 45 healthy children of similar age and distribution. In addition, mucosal immune protection against upper respiratory tract infections was assessed by measuring the concentration of secretory immunoglobulin A (sIgA) and its ratio to albumin in saliva. Several dimensions of psychosocial stress, including exposure to stressful experiences, stress-prone personality traits, and signs of emotional disturbance were elevated in children with a history of recurrent colds and flu. Furthermore, lower sIgA/albumin ratios in these children indicated a deficiency in local mucosal immunity. Thus, the findings are consistent with the view that psychosocial stress depletes local immune protection against viral invasion or bacterial colonization of the upper respiratory tract; this depletion may increase susceptibility to colds and flu. Alternatively, psychological disturbances could develop in response to frequent illness.