Lymph node dissection is an indispensable component of radical cystectomy for bladder cancer. Information obtained with lymph node dissection is highly predictive of patient survival, affecting decision-making for adjuvant therapy (diagnostic role). Also, lymph node dissection provides survival benefits in certain patients by removing metastasized nodes (therapeutic role). However, an optimal extent of lymph node dissection has not been established yet. Data from surgical mapping studies showed that approximately 10% of the primary lymphatic landing sites were common iliac nodes, suggesting that lymph node dissection below the common iliac bifurcation is suboptimal. Several retrospective studies have shown a possible survival advantage with more extended lymph node dissection. However, the results of the first prospective randomized controlled trial failed to prove the survival advantage of extended lymph node dissection up to the level of the inferior mesenteric artery, compared with lymph node dissection below the bifurcation of the common iliac artery. Currently, lymph node dissection templates recommended by major guidelines are not consistent with each other. Furthermore, the evidence is limited in the settings of neoadjuvant chemotherapy, robot-assisted surgery and high-risk non-muscle-invasive disease. Physicians need to decide the extent of lymph node dissection for each patient, taking into account the potential survival benefit and possible harms of extended lymph node dissection. Another randomized controlled trial is currently underway and will provide further evidence shortly.