Sixteen different factors that might affect the ambulatory status of patients with myelodysplasia after the age of five years were analyzed in ninety-eight patients using a linear regression technique (the Pearson correlation coefficient). Included in the study were fifty male and forty-eight female patients; the average age was fourteen years and four months (range, five years and nine months to thirty-one years and ten months). The sacral and fifth-lumbar paraplegics, with one exception, were all community ambulators. Fourth-lumbar paraplegics were usually functional ambulators, whose ability to walk was significantly influenced by musculoskeletal deformity of the spine, pelvis, hips, knees, feet, and ankles. Third-lumbar, first and second-lumbar, and thoracic level paraplegics usually were not functional ambulators. Ambulatory function was significantly influenced in third-lumbar paraplegics by hip deformity, in first and second-lumbar paraplegics by obesity and possibly by age, and in thoracic level paraplegics by age and by knee-foot-ankle deformities. Transitions in ambulatory status were usually to a lower functional level and were related to motivation, obesity, and musculoskeletal deformity. Ultimately, ambulatory status is probably related in large measure to the energy expenditure that is necessary to walk, but studies of energy requirements were not done. These findings emphasize the importance of controlling obesity as well as any musculoskeletal deformities that will influence the patient's ultimate walking ability.