OBJECTIVE To investigate the effect of extended vs standard pelvic lymphadenectomy (sPLND) for patients with intermediate- and high-risk prostate cancer undergoing laparoscopic radical prostatectomy (LRP). METHODS Of a total of 1269 patients who underwent LRP during a 109 month period, 374 (30%) had a PLND; 253 men had a sPLND (2000 to March 2008) and 121 had an extended PLND (ePLND; after April 2008) for intermediate- or high-risk prostate cancer. An extraperitoneal approach was used in all patients having sPLND and a transperitoneal approach in patients having ePLND. RESULTS Patient age, body mass index, gland weight, prostate-specific antigen level and Gleason grade were similar in the two groups. The ePLND group had a greater proportion of patients with cT3 disease (9.9% vs 4.2%, P = 0.046) and was associated with a longer operating time of 206.5 vs 180.0 min (P < 0.001) and a higher node count of 17.5 vs 6.1 (P = 0.002). Blood loss, hospital stay, transfusion and complication rates were similar in the two groups. Lymph node positivity was significantly greater (P = 0.018) in patients with pathological Gleason grade 7 tumours who had ePLND (9.6% vs 1.0%) but was similar for other grades of tumour. CONCLUSIONS Based on these findings, and the results of other studies which show a reduction of prostate cancer-specific mortality of 23% if lymph nodes are positive and 15% if they are negative after ePLND, and the correlation between surgical experience, lymph node yield and positivity, we recommend that all patients undergo ePLND if they are being treated with curative intent for intermediate- and high-risk prostate cancer; ePLND should replace sPLND and surgeons performing <35 cases of RP a year should stop performing RP.