BACKGROUND:There is currently no consensus on the indication and benefits of breathing exercises for the prevention of postoperative pulmonary complications PPCs and for the recovery of pulmonary mechanics. OBJECTIVE:To undertake a systematic review of randomized and quasi-randomized studies that assessed the effects of breathing exercises on the recovery of pulmonary function and prevention of PCCs after upper abdominal surgery UAS. METHOD: SEARCH STRATEGY:We searched the Physiotherapy Evidence Database PEDro, Scientific Electronic Library Online SciELO, MEDLINE, and Cochrane Central Register of Controlled Trials. SELECTION CRITERIA:We included randomized controlled trials and quasi-randomized controlled trials on pre- and postoperative UAS patients, in which the primary intervention was breathing exercises without the use of incentive inspirometers. DATA COLLECTION AND ANALYSIS:The methodological quality of the studies was rated according to the PEDro scale. Data on maximal respiratory pressures MIP and MEP, spirometry, diaphragm mobility, and postoperative complications were extracted and analyzed. Data were pooled in fixed-effect meta-analysis whenever possible. RESULTS:Six studies were used for analysis. Two meta-analyses including 66 participants each showed that, on the first day post-operative, the breathing exercises were likely to have induced MEP and MIP improvement treatment effects of 11.44 mmH2O (95%CI 0.88 to 22) and 11.78 mmH2O (95%CI 2.47 to 21.09), respectively. CONCLUSION:Breathing exercises are likely to have a beneficial effect on respiratory muscle strength in patients submitted to UAS, however the lack of good quality studies hinders a clear conclusion on the subject.