It is well recognised that patients with chronic pain, in particular, chronic whiplash-associated neck pain, exhibit psychological distress. However, debate continues as to whether the psychological distress precedes and causes the chronic pain or, conversely, the psychological distress is a consequence of chronic pain. Using cervical zygapophysial joint pain as a model for chronic pain, the effect of a definitive neurosurgical treatment on the associated psychological distress was studied. Seventeen patients with a single painful cervical zygapophysial joint participated in a randomised, double-blind, placebo-controlled trial of percutaneous radiofrequency neurotomy. Their pain and psychological status were evaluated pre-operatively and 3 months post-operatively by medical interview and examination, a visual analogue pain scale, the McGill Pain Questionnaire, and the SCL-90-R psychological questionnaire. All patients who obtained complete pain relief exhibited resolution of their pre-operative psychological distress. In contrast, all but one of the patients whose pain remained unrelieved continued to suffer psychological distress. Because psychological distress resolved following a neurosurgical treatment which completely relieved pain, without psychological co-therapy, it is concluded that the psychological distress exhibited by these patients was a consequence of the chronic somatic pain.