Necrosis, cysts, hemorrhage, and calcification represent common findings in renal cell carcinoma. Different lesions, including arteriosclerosis or fibromuscular dysplasia, or both, may involve the main renal artery. This study analyzed the relationship between the presence and extent of necrosis in renal cell carcinoma with renal artery changes in a consecutive series of 112 patients (71 men, 41 women) with mean renal cell carcinoma of 7.7 cm (range, 2 to 20 cm). Necrosis was seen macroscopically and confirmed microscopically in 88 cases (78.6%), with 64 tumors having less than 50% and 24 more than 50% necrosis. Fibromuscular dysplasia was found in 41 patients (36.6%; 17 men, 24 women) and atherosclerotic changes in 21 patients (18.8%; 18 men, 3 women). The results suggest that necrosis of renal cell carcinoma was significantly more common in women with associated fibromuscular dysplasia (especially type I) and men with atherosclerotic changes of renal artery.