To clarify the plantar reflex profile at 1 year of life in different categories of neurodevelopmental abnormalities, plantar responses were examined prospectively in 204 high-risk infants, of whom 58 developed cerebral palsy, 22 had developmental retardation without motor disturbance, and 124 were normal at a follow-up examination at 3 years of age. The plantar response was extensor in 82.3\% of infants subsequently found to be neurologically normal at the first month of life, becoming flexor at the age of 9 and 11 months in 68.5\% and 86.3\%, respectively. Twenty-one (42.9\%) of 49 patients with various types of spastic cerebral palsy demonstrated a combined extensor response (ie, dorsiflexion of the great toe with fanning of the remaining toes) as early as the first month of life. Children with spastic quadriplegia and hemiplegia more frequently demonstrated a combined extensor response compared to diplegic patients. The combined extensor plantar response remains a reliable prognostic clinical tool that contributes to an earlier diagnosis of spastic cerebral palsy as early as the first month of life.