e19023 Background: Hairy cell leukemia (HCL) is an uncommon and indolent leukemia of mature B cells, accounting for 2% of all lymphoid neoplasms. We analyzed characteristics, treatment modalities, response rates, and survival of HCL patients followed at our institution. Methods: We retrospectively reviewed data from the medical records of 56 consecutive HCL patients evaluated in our Hematology/Oncology clinic between 1998 and 2023. Results: The median age at diagnosis was 59 years (range, 37-94). Forty-nine patients (87%) were male. First-line therapy was cladribine in 30 patients (54%), cladribine + rituximab in 6 patients (11%), observation in 5 patients (9%), and another modality (fludarabine, pentostatin, single agent-rituximab, and other) in the rest of patients. The median follow-up was 122 months (1-291). The overall response rate was 96%. CR and PR rates were 68% and 28%, respectively. Relapses were observed in 44% of patients. The median OS was not reached, and the median PFS was 181 months (95% CI, 128-252). The 5-year and 10-year PFS were 78% and 29%, respectively. Only 3 patients (5%) died as a result of HCL, either indirectly from immune suppression (pneumonia, 2 patients) or directly (cachexia in 1 patient, untreated because of advanced age and comorbidities). Conclusions: Treatment with purine analogues such as cladribine, plus or minus rituximab, achieves deep and durable responses in most HCL patients. Although relapses were commonly observed, the vast majority of HCL patients did not die as a result of HLC.