To determine the prevalence and nature of pain in multiple sclerosis, we evaluated by questionnaire, interview, and chart review 159 patients residing in Middlesex County and followed in the MS Clinic at University Hospital, London, Ontario, Canada. Eighty-eight patients (55%) had either an acute or chronic pain syndrome at some time during their disease. Fifteen patients (9%) with acute pain syndromes had episodes of paroxysmal tic-like pain diagnosed in seven as trigeminal neuralgia. Chronic pain syndromes, present for a mean duration of 4.9 years, occurred in 76 patients (48%) and included dysesthetic extremity pain (29%), back pain (14%), painful leg spasms (13%), and abdominal pain (2%). MS patients with pain were similar to the pain-free group in mean age of onset (34.0 versus 31.9 years), average duration of disease (13.3 versus 12.1 years), spinal cord involvement (97% for each group), and mean rating on Kurtzke Disability Status Scale (4.2 versus 3.5). They differed in sex ratio with a higher female-to-male ratio in the pain group (3:1 versus 1.4:1). Chronic pain is a common feature of well-established MS and is usually associated with a myelopathy. Therapy must be individualized for each specific pain syndrome.