Although in recent years the use of purine analogues has increased the percentage of long-term complete response the effect on overall survival of patients with hairy cell leukemia (HCL) is not yet clear. This study aimed to evaluate the long-term outcome (mean follow up of 92 months) of 64 patients receiving IFN as first-line therapy. IFN was well tolerated and effective. The overall response rate was 91% (PR 65%, CR 13%, GPR 13%). Forty-one patients (63%) received IFN 3 MU/ wk as maintenance therapy. The 10-yr projected survival rate of responding patients (CR and GPR 100%; PR 95%) and non-responders (SD, PD 80%) clearly shows that type of response does not affect survival. Patients receiving IFN maintenance had a statistically higher PFS than those who did not (p
