Background: Red cell distribution width (RDW) has been shown to be associated with mortality in cardiac surgical patients. This study investigates the association of RDW with the 30-day mortality for those patients who undergo major- or ultra-major noncardiac surgery. Methods: Patients who received major- or ultra-major noncardiac surgery between July 2012 and May 2013 were included in the study and patients those with preoperative hemoglobin <10 g/day were excluded from the study. Patients were followed till day 30 from the date of surgery or death, whichever occurred earlier. Results: The overall 30-day mortality for major- and ultra-major surgery was 11.4%. The mean RDW of the 30-day survivors was 13.6 ± 1.6 and that of nonsurvivors was 14.2 ± 2.1 (P < 0.001). Other factors that were significantly different (P < 0.05) between survivors and nonsurvivors included age, sex, preoperative pulse rate, current or ex-alcoholic, the American Society of Anesthesiologists score, diabetes mellitus, use of antihypertensives, sepsis with 48 h before surgery, preoperative hemoglobin, white cell count, sodium, urea, creatinine, albumin, international normalized ratio (INR), pH, base excess, estimated blood loss, and emergency surgery. Logistic regression revealed that preoperative RDW > 13.35% (P = 0.025, odds ratio [OR]: 1.52), INR (P = 0.008, OR: 4.49), albumin level (P < 0.001, OR: 1.10), use of antihypertensives (P = 0.001, OR: 1.82), and preoperative pulse rate (P = 0.006, OR: 1.02) independently predicted the 30-day mortality. However, the area under receiver operating characteristic curve for the prediction of 30-day mortality using RDW was only 0.614. Conclusions: Although preoperative RDW independently predicted 30-day mortality in patients who underwent major- or ultra-major noncardiac surgery, it may not serve as an influential prognostic indicator in view of its low sensitivity and specificity.