The intrathecal application of the GABA-B agonist baclofen has become more and more popular for severe spinal spasticity. Since it was first introduced in 1984 more than 1000 patients worldwide have been treated by this method, using an implantable drug administration device. Clinical data from 48 patients are presented, as well as further experience from a multicentre trial conducted in Europe, in conjunction with a literature overview. The method is now generally accepted as a powerful treatment for spasticity due to spinal lesions of whatever aetiology; improvement in mobility and function as well as relief of spastic pain are the most obvious benefits for the patient. Bladder function is improved in terms of increased bladder volume and lowered residual volume. In patients with supraspinal lesions causing muscle hypertension, where several mechanisms usually contribute besides hyper-reflexia (spasticity), the response has been less pronounced, but intrathecal baclofen still seems to have clinical effects that are superior to those of any oral drug treatment. The initial technical and methodical problems have been solved and today the procedure is generally assessed as safe.