We report on an adolescent with Asperger's syndrome who developed acute pancreatitis during treatment with risperidone and citalopram. On discontinuation of psychopharmacotherapy, he fully recovered. A rechallenge testing of citalopram did not result in a relapse of pancreatitis. Other known causes of pancreatitis were not obvious. Clinicians should be alert to this rare adverse event in patients who exhibit symptoms of an acute abdominal disorder during risperidone treatment.