PURPOSE: In this report, the authors assessed the clinical significance of decreased regional cerebral blood flow (rCBF) in the thalamus or cerebellar hemispheres in relation to gross motor performance in the children with cerebral palsy. MATERIALS AND METHODS: Thirty-six children with bilateral spastic cerebral palsy (BSCP) underwent brain SPECT. Visual analysis was used for the brain SPECT interpretation. The rCBF in the thalamus or cerebellum was graded as normal, mildly decreased, or severely decreased. A marked decrease or near absence of rCBF in the thalamus or cerebellum was considered as severely decreased. RESULTS: All 36 children with BSCP had hypoperfusion in the thalamus or cerebellar hemispheres. Eight of 20 children (40\%) with mildly decreased rCBF on brain SPECT had mild developmental delays. On the other hand, only 1 of 16 children (6.3\%) with severe hypoperfusion in the thalamus or cerebellum had a mild developmental delay, and the remaining 15 of 16 children (93.8\%) had severe developmental delays. There was good correlation between the degree of developmental delay and the severity of hypoperfusion in the thalamus or cerebellum (P = 0.023). CONCLUSION: The measurement of rCBF by Tc-99m ethyl cysteinate dimer brain SPECT appears to be valuable in prognostication of gross motor development in children with BSCP.