Paroxysmal nocturnal haemoglobinuria (PNH) is an acquired haemopoietic stem cell disorder characterised clinically by chronic haemolytic anaemia with acute episodes, thrombosis and bone marrow failure. It is a rare condition, which usually occurs in younger people. Immunophenotyping and flow cytometry play a key role in diagnosing PNH. Treatment is mainly supportive. Because it is so rare, delay in diagnosis is not uncommon in patients with PNH, which has a considerable impact on patient management and prognosis. We present this case to draw attention to this rare cause of haemolytic anaemia, which should be considered in any patient, of any age, who has signs of chronic haemolysis.