Various clinical manifestations, electrophysiological findings, and sural nerve biopsies are reported in a Taiwanese family with type 1A Charcot-Marie-Tooth disease (CMT-1A). In addition, molecular genetic studies for duplication of the peripheral myelin protein 22 (PMP22) gene were also performed. There were 3 patients (2 men and 1 woman) with ages at onset ranging from 37 to 44 years. The onset of symptoms was insidious, and the neurological manifestations included distal muscle weakness and wasting, mild sensory loss, and hyporeflexia or areflexia. The severity of clinical manifestations varied from mild to severe, although with very prominent demyelinating polyneuropathy in electrophysiological studies. The sural nerve biopsy study revealed demyelination and an onion-bulb appearance. The molecular genetic studies confirmed duplication of the PMP22 gene in chromosome 17p11.2-12. We conclude that the clinical presentations, electrophysiological studies, and pathological studies as well as the molecular genetic analysis remain important in the clinical diagnosis of CMT-1A.