A retrospective study was conducted to analyze the surgical aspects of the splenectomy in chronic myelogenous leukemia. Twenty patients, Philadelphia chromosome-positive, were initially treated with busulfan until remission was reached. Elective splenectomy was then performed and chromosomal studies repeated at four- and six-month intervals yielding the indication for cyclic intensive chemotherapy. There ws no mortality, one episode of gram-negative sepsis with shock, and five instances of minimal complications. The spleen weights averaged 265 g, ranging from 60 to 800 g. All patients had normal coagulation profiles at the time of surgery, but four of them developed a postoperative thrombocytosis without related complications. A specific correlation was noted between postoperative thrombocytosis and splenomegaly (average weight 570 g). Eleven patients showed a high postoperative leukemoid reaction (average 40,500 cells/cu mm). The interval between diagnosis and splenectomy was shorter (average 7.5 months) in this group than for the patients who had a lower granulocytosis (average 19.5 months).