A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was whether incentive spirometry is a useful intervention for patients after thoracic surgery. Altogether 255 papers were found using the reported search, of which seven represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. We conclude that incentive spirometry is a relatively good measure of lung function and may be used to assess respiratory recovery in the days after thoracic surgery. Physiotherapy either with or without incentive spirometry reduces the incidence of postoperative complications and improves lung function but there is currently no evidence that incentive spirometry in itself could either replace or significantly augment the work of the physiotherapists. Clinicians should be aware that while incentive spirometry can provide an assessment of lung recovery, well-organised and regular physiotherapy remains the most effective mechanism to augment their patient's recovery and avoid postoperative complications.