The Jamshidi-Swaim biopsy needle was utilized to perform 205 bone marrow biopsies, accompanied by simultaneous bone marrow aspirates, on patients with lymphoma, leukaemia, and a variety of solid tumours. There was no significant morbidity. There were 67 positive findings with biopsy and 42 with aspiration. The two techniques were complementary in Hodgkin's disease, non-Hodgkin's lymphoma, breast carcinoma, bronchogenic carcinoma, malignant melanoma, and in leukaemia. We have examined the bone marrow biopsies and aspirates with respect to the adequacy of the bone marrow biopsy specimen, the number of positive biopsies in the various categories of neoplasia, and the disparity of biopsy and aspirate, finding that 28 of the 67 positive biopsies (41·8%) had negative aspirates. These data and specimens obtained compared quite favourably with other series in which a modification of the Vim-Silverman needle was used.