Miyoshi-type distal muscular dystrophy has now been found to be more frequent outside Japan than was previously thought. We studied 24 Dutch patients with Miyoshi-type distal muscular dystrophy and focused on its clinical expression and natural history, muscle CT-scans and muscle biopsy findings. Our study shows that Miyoshi myopathy is a heterogeneous, slowly progressive disorder. The disease starts with weakness and atrophy of the calves and progressively involves the proximal leg and hip muscles and, in a later stage the shoulder and upper arm muscles. After 10 years disease duration, one-third of the patients are dependent on wheelchairs for out-of-door transportation. Disease progression is related to disease duration and not to early age of onset of symptoms. Onset may be at any age and is asymmetrical in roughly half of the cases. Four cases had been initially diagnosed as idiopathic hyper-CK-aemia.