Yoshikawa R, et al. - A large-scale retrospective study using deidentified administrative claims data taken from 372 acute care hospitals across Japan using the Diagnosis Procedure Combination system was used in order to examine the impacts of smoking on prognosis following elective surgeries. Incidence of 30-day postoperative complications was contrasted amongst propensity score-matched "ever-smoker" and "never-smoker" cohorts. Thirty-day mortality and medical costs during the hospital stay were also contrasted. Via 561,598 eligible individuals, matched ever-smoker and never-smoker cohorts (n = 1,55,593 each) were made. The results exhibited that smoking could be related to risk of poor postoperative outcomes. Especially, a history of smoking could raise the risk of 30-day postoperative complications as well as that of 30-day mortality. Moreover, the results imply that on postoperative outcomes, smoking could have an obnoxious impact despite types of surgery.