BACKGROUND: It is well known that chest drains are associated with severe movement-related acute pain. These noxious stimuli could play a significant role in development and maintenance of persistent post-operative pain. Therefore we studied chest drain sites in post-thoracotomy pain syndrome (PTPS) patients, in regard to pain and sensory dysfunction. METHODS: We quantified thermal and pressure thresholds on both the chest drain side and the contralateral side in 11 PTPS patients and 10 pain-free post-thoracotomy patients 33 months after the thoracotomy. On average, each patient had two chest drains inserted during surgery. RESULTS: At follow up, two patients experienced pain at the chest drain sites, but had maximal pain near or at the thoracotomy scar. Comparison between chest drain side and control side for all 21 patients demonstrated significantly elevated thresholds for warmth detection and heat pain on the chest drain side (P