Data of 100 selected CGL patients were considered. There were 50 male and 50 female patients with an average 38.1 and 41.5 years of age, respectively. Seventy nine patients were in stable, chronic and 21 patients were in accelerated phase. Patients first admitted in blastic phase were excluded. Twenty two patients were subjected to bone marrow transplantation. Characteristically low levels of neutrophil alkaline phosphatase were absent in about 10 to 25% of early cases. It was considered that the level of positive cells could eventually point to the extent of normal population. In the group of the accelerated patients the neutrophil alkaline phosphatase scores were regularly high and the serum cholesterol values lower than those among stable-phase patients. The role of G-CSF (granulocyte colony stimulating factor) was considered. Secondary myelofibrosis was frequently associated with low serum cholesterol. Average survival time was 41 month among non-transplanted and 63+ months among identically-transplanted patients. In accordance with the literature, authors point out that in the presence of any factor not permitting transplantation, prolonged high-dose interferon-therapy could be the first choice, because unlike chemotherapeutic agents used till now, it prolongs survival. Apart from this autotransplantation with marrow or with circulating blood derived stem cells should be considered.