Introduction: Situs Inversus (SI) is a rare congenital anomaly that affects 1:10,000 to 1:20,000 people. It is characterized by the mirror image of the abdominal and thoracic viscera. Situs Inversus Incompletus (SII) is an abdominal heterotaxis associated with levocardia. It is a much rarer condition and accounts for 1 in 2,000,000 of the general population. Small bowel diverticulum is a rare condition, in which most patients are asymptomatic. In this report, we present a patient with IBS with an acute abdomen due to a perforated jejunal diverticulum, treated at the Hospital de Base of São José do Rio Preto, Brazil.