Identification and enumeration of individual cell types in sections of bone marrow biopsies can be difficult on haematoxylin and eosin staining. Immunohistochemistry assists in identifying cells based on antigen expression, but accurate enumeration is rarely performed. Most assessments are by imprecise “eye-ball” estimation of the number of positive events. In this presentation, I will show how the use of digital enumeration technology can accurately quantify several types of lymphoid cells and plasma cells in bone marrow trephine specimens. This work was performed on normal bone marrow trephines (n=483) obtained from patients aged one month to 90 years stained with antibodies to TdT, CD3, CD20, CD138 and MUM1. Positive cells were identified using digital enumeration technology (Digital Image Hub, Leica) and this data were used to produce standardised and normal, age-specific reference ranges. We analysed 7,210–34,097 cells (mean=16,609 cells per trephine) and could achieve positivity rates as low as 0.02%. Digital enumeration is accurate and reproducible, and enabled us to establish standardised reference ranges across the human lifespan for several lymphoid cells. We applied this digital approach to assess plasma cell burden in adults with multiple myeloma. The accuracy of digital enumeration exceeded manual estimation methods. Digital enumeration represents a highly accurate, innovative and robust medical advance which will serve as a useful adjunct in current haematology practice, particularly in resource poor settings.