A 24-yr-old, completely (T8) paraplegic male patient presenting with severe spasticity had a drug administration device implanted in April 1991 for continuous intrathecal administration of baclofen. After a period of remarkable improvement in both the spasticity level and his quality of life, the patient experienced several short-lasting episodes of increased spasticity, with severe spasms. Among the possible causes of these deleterious episodes were microcrystalluria, obstipation, a decubitus ulcer, a foreign body in the buttocks, drug tolerance to baclofen, electromagnetic interference, and erroneous filling and programing of the pump. The catheter was the most common source of intrathecal baclofen withdrawal symptoms and had to be changed four times in 5 yr. Intrathecal baclofen administered through an implantable drug administration device is a highly effective but complex and expensive procedure that requires careful patient selection and close monitoring by highly qualified and well-trained health professional. Withdrawal symptoms may be related to noncompliance on the part of the patient, erroneous filling or programing of the pump, depletion of the battery, random component failure, concomitant illness, drug tolerance, or advancement of the disease itself. When failure of the device is suspected, substitution with oral baclofen is recommended until a full work-up is performed to determine the defect.