AIMS: To assess the feasibility of training nurse practitioners to perform bone marrow aspiration and trephine biopsy, and to compare the quality of these samples with those obtained by medical staff. METHODS: A retrospective audit was undertaken of nurse practitioner and medical staff performance in bone marrow procedures in a busy haematology day unit. RESULTS: Nurse practitioners fared favourably in comparison with medical staff in performing bone marrow trephine biopsies, with mean biopsy lengths of 11 mm and 10.7 mm respectively. However, only 78% of the smears obtained by the nurses were judged technically satisfactory, compared with 91% prepared by doctors. This discrepancy was thought to be due largely to the quality of slide spreading. CONCLUSIONS: With motivated staff and a structured educational and training programme it is possible for nurse practitioners to perform the techniques of bone marrow aspiration and biopsy, and obtain specimens of satisfactory quality, thus improving efficiency of the haematology day unit and increasing quality of patient care.