Short-chain-acyl-CoA-dehydrogenase (SCAD) deficiency is an inborn error of mitochondrial fatty acid metabolism caused by rare mutations as well as common susceptibility variations in the SCAD gene. We describe the case of a 23-year-old male patient who had growth and mental retardation, recurrent vomiting, fever and seizures since infancy. Urinary gas chromatography and (1)H-nuclear magnetic resonance showed elevated levels of ethylmalonic acid. Serum concentrations of acylcarnitine, especially butyrylcarnitine (C4), were abnormally high. A homozygous variant allele of the SCAD gene, 625G>A, was detected. The patient broadens the clinical phenotype of SCAD deficiency and underlines the difficulty of diagnosis. The limited number of patients described may be the result of underdiagnosis.