We evaluated eight children with thoracic or high lumbar-level paraparesis for metabolic performance while ambulating with custom fabricated thermoplastic hip-knee-ankle-foot orthoses (HKAFOs) and reciprocating-gait orthoses (RGOs). Seven of the eight children had myelomeningocele. Each patient was tested in both systems at self-selected speeds in a crossover study design. At self-selected speeds, the level of exercise intensity for both thoracic and high-lumbar patients with either orthosis was lower than that for normal children. The average metabolic cost of walking in the RGO was twice that of normal children, as compared with six times normal in HKAFOs. For the four thoracic-level patients, there was a significantly higher oxygen cost of ambulation in using HKAFOs versus RGOs. No significant difference in metabolic performance was found for the high-lumbar patients. Velocity of ambulation was faster in the RGOs than in the HKAFOs. For thoracic-level patients, our data suggest that an RGO will provide a faster, more energy-efficient gait than a statically locked HKAFO. For high-lumbar patients, no significant difference was found between the two orthoses. Seven of eight children preferred the RGO over the HKAFO.