We investigated a possible correlation between Hoffmann's reflex (H-reflex) and the Modified Ashworth Scale (MAS) in children with spasticity. H-reflex latencies, amplitudes (H amplitude), Hmax/Mmax amplitude, and MAS were simultaneously measured in 30 children who had bilateral spasticity on the lower extremities. Children with MAS scores of 1 and +1 composed Group I (n=11), and children with MAS scores of 2 and 3 composed Group II (n=26) and Group III (n=23), respectively. The H-reflex latencies were significantly shorter and Hmax/Mmax ratios were significantly higher in patients with cerebral palsy than controls irrespective of the degree of the MAS. The H-reflex latencies in patients with MAS of 1 or +1 were significantly longer than in patients with MAS of 2. Other than between these two groups for H-reflex latencies, no significant differences were revealed among the three different MAS groups for either H-reflex latencies or Hmax/Mmax ratios. There is a positive correlation between spasticity assessed by MAS and H-reflex. We concluded that the H-reflex is a reliable electrophysiologic test for assessment of spasticity in children.