Background Direct healthcare costs of patients with symptomatic diverticular disease randomized for either laparoscopic or open elective sigmoid resection are compared. Cost-effectiveness analysis of the laparoscopic approach compared with open sigmoid resections is presented. Methods An economic evaluation of the randomized control Sigma trial was conducted, comparing elective laparoscopic sigmoid resection (LSR) to open sigmoid resection (OSR) in patients with symptomatic diverticulitis. Prospective registration of detailed intervention units per patient resulted in actual resource use per individual patient. To avoid distributional assumptions, the nonparametric bootstrap was applied. For the cost-effectiveness analysis, differences in total cost between LSR and OSR were compared with the differences in VAS pain score, SF-36 values for general health, and complication rate. Results The difference in total healthcare costs between the group that received LSR (€ 9969) and the group that received OSR (€ 9366) was not statistically significant. The slight increase in total costs was determined mainly by the significantly higher operation costs of LSR (€ 6663 vs. € 5306). Lower costs for hospitalization (€ 2983 vs. € 3598), blood products (€ 87 vs. € 240), paramedical services (€ 157 vs. € 278), and emergency attendance (€ 72 vs. € 115) in the LSR group partially compensated these increased operation costs. The incremental cost-effectiveness ratios (ICER) indicate that improvements in pain, quality of life, and complication rate could be achieved at limited costs. Conclusion Total healthcare costs of laparoscopic and open elective sigmoid resections for symptomatic diverticular disease are similar. As the clinical outcomes are in favor of the LSR group, candidates for an elective sigmoid resection should preferably be approached laparoscopically.