The paper presents experience in following up and treating hairy cell leukemia (HCL) during pregnancy. The combination of HCL and pregnancy was observed in 5 patients. The patients’ median age was 35 years (range, 28—42 years). The diagnosis of HCL was based on a conventional examination protocol: clinical blood analysis with the morphological assessment of lymphocytes, a myelogram and trepanobiopsy, immunophenotypic analysis of lymphocytes or bone marrow (in all the patients), cytochemical determination of tartrate-resistant acid phosphatase in 3 patients, and identification of BRAFV600E mutation in 3 patients. Three pregnant women were treated for HCL in the postpartum period. In one patient with HCL, pregnancy was seen in remission after treatment with cladribine. In one patient with HCL detected at 11 weeks’ gestation, interferon-α therapy during the second trimester of pregnancy was performed for increased cytopenia, which was followed by cladribine therapy after delivery. Pregnancy and delivery were uncomplicated in all the patients; 3 patients had vaginal delivery and 2 patients underwent cesarean section. All infants were healthy, with no developmental abnormalities during a follow-up period of 6—140 months (median 30 months). All the patients with HCL are currently in remission: 4 patients in first remission at a follow-up of 10 to 48 months (median 15 months) and one patient in second remission at a follow-up of 88 months. Possible observational tactics is possible when HCL is detected during pregnancy. Treatment of HCL during pregnancy is necessary in cases of deep or progressive cytopenia and/or splenomegaly. The use of interferon-α or splenectomy is preferable.