Forty-five patients, 12 men and 33 women with an age range of 17 to 88 years (median 52 years), were selected for a posterior thoracic percutaneous partial rhizotomy (PPR) based on the following criteria. Each patient had at least a 6-month history of irradiating pain that followed the segmental pattern of an intercostal nerve and had not responded to conservative treatment. In addition, no causal treatment was available and there was a temporary positive response to an intercostal blockade with lidocaine. In the lower thoracic region (T8-12) PPR was performed with the usual dorsolateral technique; in the upper thoracic region a dorsal approach was used by means of a drill hole made with a Kirschner wire in the vertebral arch. The 45 patients underwent 53 thoracic PPR operations. Patients were evaluated 2 months after treatment. Thirty patients (66.7%) were pain-free: in 11 cases (24.4%) more than 50% improvement was achieved, and in four (8.9%) there was no improvement. Side effects consisting of a transient burning pain or a mild transient sensory loss occurred in eight patients (17.7%). After a follow-up period of 13 to 46 months (median 24 months) results were evaluated in 41 patients; five patients had undergone reintervention. Excellent long-term results were achieved in 20 patients (48.8%), good results in 15 (36.6%), and poor results in six (14.6%). It is concluded, that when conservative treatment fails, thoracic PPR may prove an effective and safe treatment for chronic segmental thoracic pain.