A 3-year intensive search for selected neuromuscular disorders in Benghazi, yielded 34 patients with Duchenne's muscular dystrophy (25 index cases), 19 with limb-girdle muscular dystrophy (13 index cases), 4 with facioscapulohumeral muscular dystrophy (3 index cases), 3 with opthalmoplegia-plus (all index cases), 13 with polymyositis, 41 with hereditary motor and sensory neuropathy (HMSN) (17 index cases) and 27 with Guillain-Barré Syndrome (GBS). The age-adjusted prevalence rates, on 31 December 1985, per 100,000 population were 6 for Duchenne dystrophy, 3.7 for limb-girdle dystrophy, 0.8 for facioscapulohumeral dystrophy, 0.6 for opthalmoplegia-plus and 7.9 for HMSN (6.4 and 1.5 for Types I and II, respectively). The adjusted average annual incidence of polymyositis was 8.8/mill population; the peak incidence was observed in females in the age-group 20-40. A mean age-adjusted incidence rate for GBS of 1.7/100,000 population per year has been found. The peak age-specific incidence of GBS occurred in the third decade; the sex-dependent difference in the incidence was not significant. No indigenous forms of the disease were encountered and the clinical features differed little from the descriptions in literature. The large family size and high rate of consanguineous marriages contribute to the high frequency of familial disorders, especially those with autosomal recessive inheritance.