Net-like structures surrounding several types of neurones contain glycoconjugates which are detectable by lectins specific for N-acetylgalactosamine. Wisteria floribunda agglutinin (WFA) was introduced as a further marker for the visualization of such perineuronal nets, which were also revealed in regions of the rat brain where these structures could not be clearly demonstrated using other lectins. The WFA-labelled perineuronal nets resembled in detail those which could be visualized using Vicia villosa agglutinin, colloidal iron or hyaluronectin as markers. Furthermore, WFA-stained perineuronal net components appeared to be similar to proteoglycan-immunoreactive structures. Dual-peroxidase experiments and fluorescence double labelling demonstrated that WFA-binding structures frequently ensheath GABAergic neurons containing the calcium-binding protein parvalbumin in the areas investigated.