BACKGROUND We aimed to determine if an increased incidence of incisional hernias is present in patients undergoing sigmoidectomy for diverticulitis vs cancer. The pathophysiology of diverticulitis is poorly understood, but might involve a collagen vascular abnormality that can predispose to incisional hernia. STUDY DESIGN In this IRB-approved, retrospective study, patients who underwent sigmoid colectomies for diverticulitis or cancer between January 2003 and September 2012 were studied. Exclusion criteria included the development of surgical site infections and neoadjuvant chemoradiotherapy. A multivariate logistic regression was used with covariate adjustments for known risk factors for hernia development. RESULTS Four hundred forty-two patients (mean age 59.3 ± 13.9 years) with a median follow-up of 30 months were analyzed. The incidence of incisional hernia was 15.1% in diverticulitis patients vs 5.8% in the cancer cohort (41 of 271 vs 10 of 171; p = 0.003). Univariate analysis of risk factors associated with postoperative incisional hernia included steroid use (p = 0.007), wound packing (p = 0.001), higher American Society of Anesthesiologists classification (p = 0.001), absorbable suture closure (p = 0.02), blood transfusion (p = 0.04), stoma formation (p = 0.02), increased body mass index (p = 0.008), and history of incisional hernia (p = 0.00008). Multivariate logistic regression demonstrated a persistent association between diverticulitis and hernia development (p = 0.01). Odds of a hernia developing after sigmoidectomy for diverticulitis were 2.82 times greater than in the cancer cohort (95% CI, 1.3-6.6). CONCLUSIONS The incidence of an incisional hernia developing after a sigmoid colectomy is significantly higher when performed for diverticulitis as compared with cancer. This might be due to a connective tissue disorder, which predisposes to development of both diverticula and hernias.