Lateral pelvic lymph-node metastases occur in 10-25% of patients with rectal cancer, and are associated with higher local recurrence and reduced survival rates. A meta-analysis was undertaken to assess the value of extended lateral pelvic lymphadenectomy in the operative management of rectal cancer. We searched Medline, Embase, Ovid, Cochrane Library, and Google Scholar for studies published between 1965 and 2009 that compared extended lymphadenectomy (EL) with standard rectal resection. 20 studies, which included 5502 patients from one randomised, three prospective non-randomised, and 14 retrospective case-control studies published between 1984 and 2009, met our search criteria and were assessed. 2577 patients underwent EL and 2925 underwent non-EL for rectal cancer. Random and fixed-effects meta-analytical models were used where indicated, and between-study heterogeneity was assessed. End-points evaluated included peri-operative outcomes, 5-year survival and recurrence rates. Operating time was significantly longer in the EL group by 76.7 min (95% CI 18.77-134.68; p=0.0096). Intra-operative blood loss was greater in the EL group by 536.5 mL (95% CI 353.7-719.2; p<0.0001). Peri-operative mortality (OR 0.81, 95% CI 0.34-1.93; p=0.63) and morbidity (OR 1.45, 95% CI 0.89-2.35; p=0.13) were similar between the two groups. Data from individual studies showed that male sexual dysfunction and urinary dysfunction (three studies: OR 3.70, 95% CI 1.66-8.23; p=0.0012) were more prevalent in the EL group. There were no significant differences in 5-year survival (hazard ratio [HR] 1.09, 95% CI 0.78-1.50; p=0.62), 5-year disease-free survival (HR 1.23, 95% CI 0.75-2.03, p=0.41), and local (OR 0.83, 95% CI 0.61-1.13; p=0.23) or distant recurrence (OR 0.93, 95% CI 0.72-1.21; p=0.60). Extended lymphadenectomy does not seem to confer a significant overall cancer-specific advantage, but does seem to be associated with increased urinary and sexual dysfunction.