We describe a relatively new syndrome in four children with characteristic facial dysmorphism, sensorineural hearing loss, severe visual impairment with retinitis pigmentosa, hypotonia, hepatomegaly, and severe developmental delay. Two patients had intracranial hemorrhage secondary to a vitamin K-responsive clotting defect; both had steatorrhea. Liver biopsy specimens in two children showed an accentuated lobular architecture with prominent fibrous bands in the portal area. In one, the ultrastructure showed accumulation of abnormal substances and occasional trilaminar structures in hepatocytes and other cells. All four patients had elevated serum phytanic acid concentrations (0.3 to 2.7 mg/dl, normal less than 0.2 mg/dl) and deficient fibroblast phytanic acid oxidase activity (0.1 to 6.7 pmol/mg protein/hr, normal 23 to 87 pmol/mg protein/hr). Serum pipecolic acid was 7 to 55 times normal, and the ratio of C26/C22 very long chain fatty acids was increased (0.10 to 0.22; normal less than 0.03). This characteristic syndrome has been described in several children and called infantile Refsum disease or phytanic acid storage disease. Its relationship to neonatal adrenoleukodystrophy, hyperpipecolic acidemia, and Zellweger syndrome is discussed.