Objective. To assess the effect of smoking on postoperative complications following elective primary total hip replacement (THR) or primary total knee replacement (TKR). Methods. We used data from the national Veterans Affairs Surgical Quality Improvement Program to examine the association of smoking status at surgery with 30-day postoperative complication rates (including surgical site and other infections, pneumonia, stroke, myocardial infarction, mortality, and other complications) in veterans undergoing primary elective THR or TKR. Multilevel multivariable-adjusted logistic regression models, adjusted for age, race/ethnicity, work relative value units, American Society of Anesthesiology classification, and year of surgery, with additional adjustment for wound classification for surgical site infections, were used. Results. A total of 33,336 patients, 95% men and 80% white with a mean age of 64 years, underwent elective primary THR/TKR between October 2001 and September 2008. Fifty-seven percent never smoked, 19% were prior smokers, and 24% were current smokers. Current smokers undergoing THR/TKR were significantly more likely than never smokers to have surgical site infections (odds ratio [OR] 1.41, 95% CI 1.16-1.72), pneumonia (OR 1.53, 95% CI 1.10-2.14), stroke (OR 2.61, 95% CI 1.26-5.41), and 1-year mortality (OR 1.63, 95% CI 1.31-2.02). Prior smokers were significantly more likely than nonsmokers to have pneumonia, (OR 1.34, 95% CI 1.00-1.80), stroke (OR 2.14, 95% CI 1.12-4.10), and urinary tract infection (OR 1.26, 95% CI 1.02-1.55). Conclusion. Current smoking at the time of elective THR or TKR is associated with increased postarthroplasty complications, especially surgical site infections and pneumonia. Preoperative smoking cessation programs should be considered in patients undergoing elective THR or TKR. © 2011. American College of Rheumatology.