A premature boy with a congenital form of nemaline myopathy due to mutation in the ACTA1-gene showed decreased carnitine levels in the eighth week of life. After sufficient oral carnitine substitution he improved gradually. In the first 15 months of life he made good progress; he reached full head control, learned to sit unsupported and was able to raise objects. At that time the carnitine levels were normal without substitution. Nemaline myopathy is clinically and genetically heterogenous. The pathogenesis of the muscle weakness is poorly understood. Disturbances of carnitine metabolism in this group of patients as one possibility are conceivable. Further investigations of carnitine metabolism in patients with nemaline myopathy may shed light on the pathogenesis of this entity.