This paper describes a case of spontaneous rupture of the spleen that was misdiagnosed as pulmonary embolism. Because of a lack of history of trauma, rarity of occurrence, and confusing clinical presentations, an unwary clinician may fail to diagnose this condition in time. It may result in erroneous treatment of a condition, which is potentially curable.A 48 year old computer engineer presented to the accident and emergency department with lower chest and upper abdominal pain of 40 minutes' duration. The pain started an hour after he had eaten his supper, while sitting at home. The pain was sharp and severe in nature; there was no radiation, no associated aggravating or relieving factors. He felt tightness and discomfort around the chest. There was no significant medical history. On arrival his blood pressure was 96/46 mm of Hg; pulse rate 90/min and regular; respiratory rate 26/min. Examination of the chest confirmed good bilateral air entry without any adventitious sounds. Abdominal examination revealed moderate tenderness in epigastrium but no rebound; there was no rigidity and bowel sounds were present. Laboratory investigations revealed a haemoglobin concentration of 128 g/l, leucocyte count of 11.9×10 9 /l, platelet count of 340×10 9 /l, normal values of urea, electrolytes, amylase, and cardiac enzymes. Arterial blood gas analysis showed acute respiratory alkalosis and hypoxia. Erect chest rdiography was normal and did not show any free gas under the diaphragm. There was suspicion of slight changes in the electrocardiogram (S 1 Q 3 T 3 ) but no changes suggestive of acute myocardial infarction.He was transferred to the surgical ward in view of abdominal pain. However, the clinical features and investigations were not conclusive. A medical opinion was obtained. Pulmonary embolism was thought to be the provisional diagnosis. Therefore, in addition to supportive treatment, he was given intravenous heparin. On review six hours later, his main complaint appeared to be upper abdominal pain. He was no longer complaining of any chest symptoms. Abdominal examination revealed rigidity and rebound tenderness in the upper abdomen. It was becoming clear that the underlying disorder was intra-abdominal rather than intrathoracic.A perforated hollow viscus was thought to be the most probable diagnosis. At emergency laparotomy a large subcapsular haematoma was found near the splenic hilum, which had ruptured the splenic capsule. No peri-splenic adhesions or scarring of spleen were noted. The total blood loss was 1400 ml and he required three units of packed red cell transfusion. A splenectomy was performed. The spleen was not enlarged and found to be normal, both macroscopically and microscopically. His postoperative recovery was uneventful.