Xp21 contiguous gene deletion syndrome involves the glycerol kinase (GK) gene, adrenal hypoplasia congenital (AHC) gene and Duchenne's muscular dystrophy (DMD) gene, which are located contiguously on Xp21 chromosome. The clinical features of a patient with Xp21 contiguous gene deletion syndrome are the sum of those of each disease; psychomotor retardation and lethargy for GK deficiency, hyperpigmentation and salt wasting dehydration for AHC, and muscular weakness and hypotonia for DMD. Chromosomal microarray analysis is performed for confirmation of Xp21 contiguous gene deletion syndrome. The goal of treatment is to control each of the diseases. We experienced and reported on a neonatal case of Xp21 contiguous gene deletion syndrome of AHC, GK deficiency, and DMD.