We studied the prevalence of various types of progressive muscular dystrophy (PMD) in Okinawa, Japan on December 31, 1989 and the incidence of Duchenne muscular dystrophy (DMD) in 5-year periods from 1957 to 1985. We classified patients with PMD clinically, electrophysiologically, molecular biologically and immunohistochemically with antidystrophin antibody, especially for sporadic cases of DMD, Becker muscular dystrophy (BMD) and limb-girdle muscular dystrophy (LG). The prevalence for all PMD in Okinawa was 7.13 X 10(-5) for DMD, 1.82 X 10(-5) for BMD in the male population, 1.55 X 10(-5) for LG, 1.14 X 10(-5) for congenital muscular dystrophy, 2.03 X 10(-5) for facioscapulohumeral muscular dystrophy (FSH), and 9.13 X 10(-5) for myotonic dystrophy (MD) in the total population. The incidence of DMD in the period 1957-1985 was 15.41 X 10(-5) live-born males (LBM) and 3.21 X 10(-5) LBM for BMD. The incidence has apparently declined in Okinawa since 1975. The prevalence of BMD, FSH and MD was rather high in Okinawa compared with previous reports. Molecular biological techniques for classifying patients were indispensable for the epidemiological study of PMD.