Pulmonary function testing (PFT) has not been listed as a risk for development of incarceration in an existing inguinal hernia. We report two patients who developed this complication after routine preoperative PFT. We also present data of our retrospective review of eight patients with inguinal hernia who were referred for preoperative PFT. Two out of eight patients suffered incarceration of an existing inguinal hernia. We found no significant difference in mean age, weight, smoking habits, number of forced expiratory maneuvers, time of sustained forced expiratory maneuver, or any PFT data between the groups with and without incarceration. Thus, incarceration of inguinal hernia could not have been predicted prior to PFT and was not related to other factors such as obesity or more severe airway obstruction.