BACKGROUND: We evaluated the influence of infectious complications, particularly surgical site infection (SSI), on long-term oncological results after elective laparoscopic resection of colorectal cancer. METHODS: A total of 199 patients who underwent laparoscopic elective resection with negative resection margins for stage I-III colorectal cancer were retrospectively examined. The postoperative course was recorded based on hospital records, and cancer relapse was diagnosed based on radiological or pathological findings under a standardized follow-up program. The severity of complications was graded using Clavien-Dindo (CD) classification. RESULTS: SSI was found in 25 patients (12.6%), with 12 (6.0%) showing anastomotic leak. The postoperative relapse-free survival (RFS) rate was significantly lower in patients with SSI (49.2%) than in patients without SSI (87.2%, P<0.001). Differences in RFS were found after both colectomy and rectal resection (P<0.001 and P<0.001, respectively). RFS did not differ between patients who had major SSI CD (grade III) and those who had minor SSI CD (grades I or II). Multivariate Cox regression analysis identified the occurrence of SSI and pathological stage as independent co-factors for RFS (P<0.001 and P=0.003). CONCLUSION: These results suggest that postoperative SSI compromises long-term oncological results after laparoscopic colorectal resection. Further improvements in surgical technique and refinements in perioperative care may improve long-term oncological results.