We report on a case of hereditary pyropoïkilocytosis fortuitously diagnosed in a 34-year old woman issued from Benin. Laboratory tests indicated a moderate haemolytic anaemia with a marked microcytosis. Blood film examination revealed a striking anisopoikilocytosis characterized by elliptocytes, numerous red blood cells (RBC) fragments and microspherocytes. The histogram of RBC volume distribution showed two populations of RBC: a normocytic and a very microcytic population, this later corresponding to the RBC fragmentation. These features strongly suggested a membrane disorder, particularly an hereditary pyropoïkilocytosis (HPP). The thermal unstability of the cytoskeleton was demonstrated by enhanced red cell fragmentation after in vitro exposure to heat which occurs at a lower temperature as compared to normal red cells. The diagnosis of HPP was confirmed by specialized investigations (osmotic gradient ektacytometry and erythrocytic membrane proteins electrophoresis). HPP is considered as a severe form of hereditary elliptocytosis characterized by jaundice and a severe haemolytic anaemia which usually appears during the neonatal period and the childhood. Our report is intriguing because of the delayed diagnosis of HPP in a patient who presented moderate clinical manifestations.