Neurofilamentous tangles have been induced in cultured neurones from rat brain hemispheres by application of both aluminium and maltol. Quantitative evaluation revealed a significantly higher percentage of tangle containing neurones when using the aluminium-maltol mixture than after application of aluminium alone. Tangles were found to be consistently stained with monoclonal antibodies to neurofilament proteins but failed to react with polyclonal antibodies against microtubule-associated proteins 1, 2 and tau.