Objective: Patients with nontraumatic spinal cord lesions account for between one fourth and one half of all spinal cord injuries. In the management of this group of patients, an understanding of factors influencing functional improvement is essen tial to help define the most appropriate rehabilitation programme. Although it is pos sible to predict accurately the functional outcome for an individual patient with a com plete traumatic spinal cord injury, few studies have looked at prognostic factors in patients with nontraumatic spinal cord disease. The aim of this study was to determine which, and how well, factors assessed on admission to a rehabilitation unit relate to functional improvement in this group. Methods: The study sample consists of 100 patients with an incomplete nontraumatic spinal cord lesion who underwent inpatient neurorehabilitation. Possible prognostic factors were sought by identifying those vari ables with a significant difference in the Functional Independence Measure (FIM) motor change score above and below the median. A step-wise multiple regression analysis was then performed to determine which variables influenced functional out come. Results: Patients with larger functional gains had significantly lower disability scores on admission, a shorter time between symptom onset and rehabilitation, and a longer length of stay. They were more likely to have a cervical lesion and evidence of neurologic recovery. Multiple regression analysis demonstrated that the FIM motor score on admission and the time between symptom onset and rehabilitation predicted 54% of the variance of the FIM motor score gain. Conclusions: This finding suggests that early rehabilitation is an important factor in securing a good outcome. Key Words: Rehabilitation-Spinal cord lesion-Functional outcome.