We performed a survival analysis of 155 cases of progressive muscular atrophy (PMA). In about half the cases, hands were involved first, the lower limbs in 30% and the shoulder girdle in 23%. The lifetables of PMA, adjusted to the expected mortality, showed a survival rate of 61.3% and 56.4% at three and five years, respectively. The location of onset symptoms did not modify the life expectancy, whereas the age of the patients at the moment of first diagnosis had a great influence on the course of the disease. The patients were further subdivided in two groups on the basis of the diffusion of the neuromuscular damage at the moment of the diagnosis. The course of the patients with a localized disease was markedly better than that of subjects with widespread disease. Some hypotheses are made about the latter group of cases.