To present our experience with laparoscopic heminephrectomy. We defined heminephrectomy as excision of 30% or more of the renal parenchyma. Laparoscopic partial nephrectomy has typically been performed for smaller, exophytic tumors. With growing experience, we have performed more extensive resections for larger tumors, when indicated. Since August 1999, we have performed laparoscopic partial nephrectomy in more than 300 patients. Of these, 41 patients were deemed to have undergone laparoscopic heminephrectomy (group 1). A contemporary group of 41 consecutive patients who underwent laparoscopic partial nephrectomy (less than 30% resection) were retrospectively identified for comparison (group 2). The preoperative patient demographics were similar, except for a greater body mass index (P = 0.02) in group 1. Group 1 had larger tumors (3.7 cm versus 2.3 cm, P <0.001) that were more commonly centrally located (41% versus 9.8%, P = 0.001) and more deeply infiltrating (P <0.001) compared with group 2. Group 1 underwent larger parenchymal resections (P <0.001) and routine pelvicaliceal suture repair (P = 0.002). The warm ischemia time was longer in group 1 (39 versus 33 minutes, P = 0.02); however, the amount of blood loss (150 versus 100 mL, P = 0.28) and total operative time (220 versus 190 minutes, P = 0.09) were comparable between the groups. The analgesic requirements, hospital stay, overall complications, and postoperative serum creatinine were comparable between the groups. Histopathologic examination showed that all 82 surgical margins were negative. Laparoscopic heminephrectomy is an advanced procedure that can be performed efficaciously with equivalent outcomes to those of less substantial resections. To our knowledge, experience with laparoscopic heminephrectomy has not been previously described.