Spontaneous splenic rupture is an unusual complication of hematologic malignancies with a high mortality rate. We report two cases of non-traumatic splenic rupture: the first one was a patient with myelomonocytic leukaemia and the second one a previously undiagnosed patient with non Hodgkin's lymphoma, both of them survived after splenectomy. Emphasis on the necessity of an early diagnosis and treatment are made.