Background: In a retrospective analysis we investigated the prognostic significance of the interval between first appearance of motoric deficits and the beginning of radiation therapy (RT) with regard to posttreatment motoric function. Material and Methods: Data of more than 400 consecutive patients being irradiated at our department between 1994 and 1997 because of vertebral metastases were reviewed. Ninety-six patients fulfilled selection criteria including motoric deficits, no preceding surgical or radiotherapeutic treatment of the spine, minimum total dose of 24 Gy referred to spinal cord, and additional treatment with dexamethasone. Two subgroups with a similar number of patients for better comparability were formed according to the time of developing motoric deficits: 1 to 13 days (49 patients) and ≥14 days (47 patients). Effect of irradiation on motoric function was evaluated 2 weeks and about 3 months after radiotherapy. Patients with severe deterioration of motoric function within 48 hours before radiation therapy (31 patients) were looked at separately. Results: Two weeks after radiotherapy 42/47 patients (89%) developing motoric deficits ≥ 14 days showed improvement of motoric function in comparison to 6/49 patients (12%) of the other group. Deterioration occurred in 1/47 patients (2%) of the first and in 24/49 patients (49%) of the latter group. In case of severe deterioration of motoric function within 48 hours before radiation therapy only 2/31 patients (6%) showed improvement, but 20/31 (65%) deterioration. About 3 months after radiotherapy comparable results were observed. Median survival time was 4 months. Conclusion: A slower development of motoric deficits before beginning of radiotherapy means a better therapeutic effect and a more favorable functional outcome after treatment. The prognosis is extraordinarily poor if severe deterioration of motoric function occurs within 48 hours before radiotherapy.