Primary cultures were established from autopsy or biopsy samples of normal adult human brain and characterized by immunocytochemical techniques. Initially, macrophages were the predominant cell type adhering to the substratum, but as their number fell that of glial cells increased. Oligodendrocytes comprised 30% of the glial population in white matter cultures, and their perikarya and elongated processes were immunostained with antibodies directed against galactocerebroside and four myelin proteins. In white and grey matter cultures, process-bearing astrocytes and small numbers of polygonal astrocytes were stained with antibodies against glial fibrillary acidic protein and glutamine synthetase. Fibroblasts started to appear at 3 weeks and proliferated to form a monolayer beneath glial cells by 5 weeks. Glia began to die in the 6th week. These primary cell cultures of white or grey matter can be used to study the properties of glial cells from normal or pathological adult human brain.