Glutaric aciduria type 1 is an autosomal recessive metabolic disease that is due to a deficiency of glutaryl-Co-A dehydrogenase in the metabolism of lysine, hydroxylysine and tryptophane. It usually appears as the loss of gained motor skills, a previously well child suffering spastic cerebral palsy, choreoathetosis, dystonia and mental retardation following a febrile illness associated with acute mental deterioration in the first three years of life. Less commonly, it may clinically appear as a progressive course of mental deterioration or isolated macrocephaly. Here, we report a 23-month-old boy who could not speak or walk and an eight-month-old girl with seizures and loss of previously gained motor skills. The two cases, having frontotemporal atrophy and basal ganglia degeneration on cerebral magnetic resonance imagings, and increased glutaryl-carnitine, glutaric and 3-hydroxy glutaric acid levels in tandem-mass spectrometer and urine organic acid quantification by gas chromatography, were diagnosed as glutaric aciduria type 1. We report these two cases to emphasize that it is a rare disease and must be considered in the differential diagnosis of cerebral palsy. Anahtar Kelimeler : glutarik asidüri tip 1, frontotemporal atrofi, ayırıcı tanı, serebral palsi, glutaric aciduria type 1, frontotemporal atrophy, differential diagnosis, cerebral palsy