Phlebotomy is the most commonly treatment used for erythrocytosis and polycythaemia. After the introduction in the medical practice of cell separators, erythrocytapheresis has been also introduced. The aim of the study was to compare the clinical results of the two kinds of treatment.We analysed 98 patients affected by different forms of erythrocytosis, divided into three treatment groups: 1) patients undergoing phlebotomy; 2) patients treated only with therapeutic erythrocytapheresis; 3) patients who underwent phlebotomy treatment for a certain period and who were then switched to apheresis treatment. The haematocrit in these patients was maintained at about 45% and they were treated when the haematocrit exceeded the critical threshold of 50%.The interval between two therapeutic interventions was assumed as indicator. In 80% of the patients treated only with phlebotomy the interval was between 20 days and 2 months, in subjects treated with only erythrocytapheresis the intevals were between 2 and 7 months. In the third group of patients, the switch from phlebotomy to erythrocytapheresis considerably prolonged the interval.The data showed that erythrocytapheresis was clearly superior to traditional phlebotomy in terms of prolonging the period between one treatment and another, independently of the type of erythrocytosis and of the treatment group.