The aim of the study was to assess the incidence and clinical features of headache associated with the use of granulocyte colony-stimulating factor (G-CSF) for stem cell mobilization or neutropenia treatment among oncohematological patients and bone marrow donors.Material and methods. A prospective observational uncontrolled study included 39 participants: 20 bone marrow donors (group 1) and 19 oncohematological patients (group 2). We evaluated the incidence and clinical features of headache after subcutaneous administration of G-CSF (filgrastim) at doses of 5 to 10 μg/kg for 2 to 5 days.Results. Headache occurred in bone marrow donors more often compared to patients with hematological malignancies (78.9% vs 35.0%; p = 0.006). There were no significant differences in the time of headache onset, its duration, intensity, features, and localization between two groups. Gender, age, dose of G-CSF, and duration of its use were not associated with headache development in both groups.Conclusion. Headache occurs more often in bone marrow donors than in patients with hematological malignancies. The phenotype of headache associated with G-CSF exposure is not drug-specific and requires further studies on its semiotics.