Background: Surgical removal of huge renal and retroperitoneal tumors, such as adrenal cortical carcinoma or renal cell carcinoma with inferior vena cava (IVC) invasion, remains a challenge for urologists. Aim: Herein, we describe our experience with the modified Makuuchi incision for huge renal and retroperitoneal tumors. Methods: We applied the modified Makuuchi incision in 10 patients with a huge renal or retroperitoneal tumor. Another 11 patients with a huge renal or retroperitoneal tumor using different surgical incisions other than modified Makuuchi incision were collected for comparison. The modified Makuuchi incision of the abdomen is initiated in the cephalad to the xiphoid, extended 1 cm above the umbilicus, and then extended laterally to the lateral flank. Through the incision, we mobilized the colon, and when the renal space was seen, the tumor was removed. If an invasion of a nearby organ occurred, a general or cardiovascular surgery specialist was consulted for combined surgery. The patients’ age ranged from 43 to 82 years (three men and seven women). Results: The modified Makuuchi incision provided good and rapid exposure. No unexpected organ injuries occurred during surgery. There were no wound related complications, such as dehiscence or incisional hernia, after 3 months of follow up. Partial hepatectomy, splenectomy, distal pancreatectomy, and thrombectomy of the IVC thrombus were performed through the same incision. Conclusion: Our experience demonstrated that the modified Makuuchi incision is a good choice for patients with huge renal and retroperitoneal tumors, even those with nearby organ invasion.