In a case of subacute sensory and motor polyneuropathy associated with sarcoidosis, multiple epineurial and endoneurial granulomas were demonstrated in a sural nerve. Neighbouring nerve fibres were displaced by the granulomas and some were undergoing axonal degeneration. Ultrastructural and teased fibre studies showed axonal atrophy and degeneration with secondary demyelination. Histochemical studies indicated the presence of HLA-DR antigen on epithelioid cells in the granulomas. A non-specific inflammatory process in the nerve does not cause significant primary demyelination.