Neonates with proximal arthrogryposis are likely to have amyoplasia congenita. Neonates with distal arthrogryposis present a complex diagnostic problem. Most neonates with distal arthrogryposis can only be diagnosed by recognizing a constellation of signs leading to the diagnosis of a syndrome. Few neonates with distal arthrogryposis have specific laboratory findings. Zellweger syndrome courses with increased very-long-chain fatty acids in plasma. Smith-Lemli-Opitz syndrome courses with high levels of the cholesterol precursor 7-dehydrocholesterol and low cholesterol levels. Trisomies are associated with chromosomal abnormalities. Walker-Warburg syndrome is associated with characteristic magnetic resonance imaging abnormalities. Spinal muscular atrophy is diagnosed by DNA testing. Spinal cord abnormalities may be detected by MRI of the spine. Congenital hypomyelinating neuropathy is diagnosed by nerve conduction studies. Schwartz-Jampel syndrome courses with electromyographic myotonia and bone dysplasia. Sodium-channel myotonia and myotonic dystrophy may course with electromyographic evidence of myotonia.