The light microscopic and ultrastructural features of cultured meningioma cells were compared with those of surgically resected specimens. Meningioma cells normally show variable degrees of epithelial or mesenchymal differentiation. In cultured cells, well formed psammoma bodies and whorls were seen by light microscopy and specialised intercellular junctions were observed by electron microscopy. Cytogenetic analysis was also shown to be a useful diagnostic marker to differentiate cultured meningioma from contaminant proliferating fibroblastic and endothelial cells. These methods have demonstrated that the cells cultured from operative samples were predominantly meningioma cells. The ability to reproducibly cultivate populations of meningioma cells should facilitate in vitro assessment of potential adjunctive treatment modalities.