Pupillary reactivity was employed as a measure of autonomic nervous system responsivity in 12 well children and 13 children with recurrent abdominal pain. Dilatation of the pupil in darkness was measured as an index of adrenergic reactivity during experimental rest, under stress, and after recovery from stress. No significant difference between the two groups was observed at rest. In response to stress both groups showed a further increase in pupillary dilatation to a similar degree. A significant difference after stress was manifested as a small initial decrement of pupillary dilatation in the children with abdominal pain. It is suggested that the mechanism for drive reduction after stress is aberrant in children with recurrent abdominal pain.