The expression of 72-kDa heat shock protein (HSP72) in cultured mouse oligodendrocytes and astrocytes exposed to heat shock was investigated by double immunolabelling with anti-HSP72 monoclonal antibody (C92F3B-1) and antibodies against galactocerebroside (GalC) or glial fibrillary acidic protein (GFAP). After 3 h recovery from heat shock, an intermediate level of HSP72 immunolabelling was localized in the nucleolus and cytoplasm of astrocytes (<25%) and to a lesser extent in oligodendrocytes (<2%). After 8–48 h, HSP72 was expressed intensely in the cytoplasm and nuclear matrix of oligodendrocytes (20–40%), while weak/intermediate immunostaining was detectable in astrocytes (5–15%). The levels of HSP72 expressed in oligodendrocytes and astrocytes decreased around 72–120 h, but a few oligodendrocytes (4%) remained intensely immunolabelled. These results indicate that heat shock induces HSP72 in both oligodendrocytes and astrocytes. However, this response is heterogeneous.