Nine patients with the characteristic signs of fetal akinesia sequence (polyhydramnion, multiple joint contractures and lung hypoplasia) are described. In 8 of the 9 patients nemaline myopathy could be demonstrated with histology. The ninth patient presented the same phenotype as his 4 affected siblings in whom the nemaline myopathy could be histologically proven. Seven of the patients belonged to 2 families; the other 2 patients were isolated cases. In one fetal case nemaline myopathy was documented at week 22 of gestation. These observations demonstrate that nemaline myopathy can cause the fetal akinesia sequence, with onset of first symptoms as early as the beginning of the second trimester of pregnancy.