We present the case of a diver who experienced the acute onset of shoulder pain after a rapid ascent. It was determined that the patient had decompression sickness ("the bends") of the right shoulder and pulmonary barotrauma resulting in secondary pneumoperitoneum. He underwent decompression, with prompt resolution of symptoms. Of the 14 cases of isolated pneumoperitoneum due to barotrauma reported in the world literature, three were due to gastric rupture. Shoulder pain in association with pneumoperitoneum may be due to diaphragmatic irritation or may be an isolated symptom of decompression sickness. Correctly determining the etiology of these findings is crucial to the appropriate management of the patient.