Techniques of chest physical therapy have been used since the early 1900s to decrease postoperative pulmonary complications. Through investigations since the 1950s, documentation as to the efficacy of chest physical therapy in actually reducing postoperative pulmonary complications has been published. However, the careful documentation of techniques employed (such as full Trendelenburg's position versus a modified position and vibration of particular force and frequency) has not been done. Also, because of an inability to specify the risk factors of postoperative pulmonary complications occurring in particular patients or to qualitate the occurrence of these complications, it is difficult to establish what treatment is most efficacious. This article is a critical review of investigations to date with recommendations for further research stemming from this review.