Angiogenesis, the creation of new blood vessels from preexisting vascular nets, plays a major role in the development, progression and dissemination of solid malignant tumors. Research over the last few years has shown a correlation of angiogenesis and the biological behaviour of haematologic malignancies. This study focused on the relation of vasoformation, stage of differentiation of tumour plasmocytes and type of bone marrow infiltration in patients with multiple myeloma (MM) prior to treatment. We evaluated trephine biopsy samples from 55 patients for microvessel density in 1 mm2 field by monoclonal antibody anti CD34. Angiogenesis correlated with the type of infiltration and with stage of morphological differentiation. It was highest in the nodular type of infiltration with a low level of differentiation, and lowest in grade 1 differentiation with an interstitial type of infiltration.