Several studies have been reporting circadian variation in postoperative morbidity and mortality. We investigated whether the outcomes after off-pump coronary artery bypass (OPCAB) surgery are influenced by the operation start time.We retrospectively evaluated 1690 patients who received elective OPCAB surgery from January 2006 to December 2016. The patients were divided into two groups according to the operation start time (morning or afternoon). The primary outcome was the occurrence of a major adverse cardiac event (MACE) within 30 days after surgery and death within 1 year after surgery. Propensity matching analysis and multivariable analyses were performed to evaluate the relationship between the operation start time and postoperative outcomes.There were no significant differences in the overall 1-year mortality rate (2.2% vs 2.9%; P = .568 in the entire cohort and 1.5% vs 2.7%; P = .259 in the propensity-matched cohort) and 30-day MACE rate (8.9% vs 10.4%; P = .378 in the entire cohort and 9.4% vs 10.0%; P = .827 in the propensity-matched cohort) between the morning and afternoon surgery group. Multivariable regression analyses also did not show any significant relationship between the operation start time and postoperative outcomes.In elective OPCAB surgery, the operative time was not associated with an increased risk of postoperative mortality and complications.