Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired disorder of blood cells which originate from an abnormal hematopoietic stem cell. The condition is characterized by nocturnal hemoglobinuria, chronic hemolytic anemia, and thrombosis. We describe a 60-year-old woman with PNH admitted with abdominal pain and jaundice, who had dark urine on arising after a night's sleep. The diagnosis was established by the typical clinical story and a positive Ham test. She was successfully treated with Halotestin and folic acid. Although PNH is rare, it should be considered in the differential diagnosis of hemolytic anemia. Early diagnosis and treatment are important.