Renal cell cancer accounts for 2% of all new cancer cases worldwide. Incidence rates have been rising steadily around the world. In the United States, the rates have been rapidly increasing among black Americans, whose incidence rate has now surpassed that of white Americans. Cigarette smoking and obesity are the most consistently established causal risk factors, accounting for more than 20% and 30% of renal cell cancers, respectively. Hypertension, rather than antihypertensive drugs, appears to influence renal cell cancer development, although the mechanism is unknown. Analgesics have not been convincingly linked with renal cell cancer risk. In general, there appears to be a protective effect of fruit and vegetable consumption, although no particular component of diet has been clearly implicated. There are sporadic and inconsistent reports of occupations or occupational exposures being associated with this cancer. Epidemiologic studies are needed to identify reasons for the increasing incidence of renal cell cancer, with particular focus on why the incidence rate for black Americans has risen to significantly surpass that of white Americans.