Urological problems in M.S. patients are very frequent and are usually very disabling. Complaints will often be misleading. Urodynamic investigations play a most important part in the diagnosis but are carried out with more difficulty than in other patients. The lower urinary tract dysfunction is classified as advised by the I.C.S. Committee. Detailed figures are given in the text. Evolution of urological disorders in M.S. is unpredictable. Treatment has to be conservative, flexible and reversible if possible. The goal of the treatment is to get a balanced bladder and complications due to urological manipulations must be avoided.