A retrospective analysis of the treatment with Interferon alpha in 18 patients with Ph positive chronic myeloid leukaemia is presented and compared with the results of peroral chemotherapy with Hydroxyurea or Busulphan in 20 patients. Patients treated with Interferon were significantly younger than the control group (median age 40.5 versus 55.5) (p = 0.01) and were followed-up for shorter period of time (median 10.5 months versus 36.5 months) ( p = 0.002), but did not differ in other parameters. Despite the shorter period of observation and treatment, significantly more complete haematological remissions were achieved with Interferon (86%) than with peroral chemotherapy (25%) (p = 0.03). 6 major and 2 minor (44%) cytogenetic responses were observed after Interferon, despite the fact that 8 patients had been treated for less than one year. Interferon was not the optimal therapy in the patients with additional or complex cytogenetic abnormalities at the time of diagnosis, which were the most significant negative prognostic factor. In general, our short-term results confirm the importance and effectiveness of Interferon in the patient with CML providing the therapy was started early, with an effective dose and with simultaneous cytogenetic monitoring. Longer observation of the patients is needed to confirm the impact of Interferon on the survival of patients.