Morphological changes in human skeletal muscle with ageing are reported. Samples from the deltoid and the vastus lateralis muscles from 126 subjects, aged 20-80 years, were studied by light microscopy. The patients died suddenly due to accidents or from fatal diseases. Until their death, they had preserved normal physical activity corresponding to their age. Chronic diseases, inactivity or neuromuscular diseases which are known to lead to changes in the muscles were excluded. The frequency of neurogenic changes of muscles increased with increasing age. These results correlated with electrophysiological and morphological changes in the peripheral nerves due to ageing reported by other investigators. The neurogenic changes in persons over 70 years were overlapped by a type-2 fibre atrophy.