The study was aimed to assess the efficacy of busulphan treatment in patients with polycythemia rubra vera (PRV). The group of 74 patients (mean age 60 years, range: 40-81) was studied, including 38 females, 36 males. The remission was achieved in all cases; the mean time of remission was 33 months (range 3-200), the mean busulphan dose necessary to reach the first PRV remission was 266 mg (range: 76-600). The associations between hemoglobin level, white blood cells, neurocytes, platelet counts at diagnosis and the mean cumulative busulphan dose necessary to obtain the first PRV remission as well as between above parameters and the mean duration of the first PRV remission was estimated. The mean duration of the first PRV remission was significantly (P < 0.03) longer in patients with neurocyte count below 9.6 G/l (9.6 x 10(3)/mm3) as compared to those with higher levels; except it, no relationship were noticed between above parameters. The results of the study confirmed that busulphan is an effective and safe drug for patients with PRV.