6 patients with severe chronic progressive multiple sclerosis were subjected to total lymphoid irradiation (TLI) to assess clinical efficacy and side effects. During a 4 year follow-up the disability progression was continuous. Side effects during TLI were well tolerated; side effects after TLI brought about a worsening of the quality of life. One patient died of pneumonia. In this preliminary study TLI did not reduce the worsening of disability in MS patients.