Clinical, biochemical, functional and morphological data are presented in nine infants, children and adults, with Fanconi-Bickel syndrome. Long-term follow-up studies show severe growth retardation, partly compensated for by late onset of puberty. Glomerular filtration rate is normal or slightly decreased. Renal tubular dysfunction is characterized by a specific pattern of impaired proximal tubular transport mechanisms, with marked impairment of glucose transport. The utilization of glucose and galactose is defective, whereas fructose metabolism seems to be normal. Glycogenosis of the liver may be an epiphenomenon. Glycogen accumulation in the kidney is limited to the proximal tubule, with maximal levels in the straight part. The Fanconi-Bickel syndrome is a defined clinical entity which is distinguished from other inherited metabolic diseases by complex defects of renal tubular transport and other forms of glycogenosis.