Serum cholesterol as risk factor for premature mortality; 0--6, mean 3 years after a screening investigation in 10,000 middle-aged men (46--48 years at screening) was studied with respect to category of death. Serum cholesterol was reciprocally correlated to cancer deaths and to alcohol-related deaths, and strongly positively correlated to deaths in coronary heart disease. The men who died of cancer did not have lower body weight, nor was there any association with serum triglycerides. The inverse correlation to serum cholesterol did not differ between the cancer deaths occurring early, and those occurring later after screening. Part of the cholesterol/cancer death relationship may be explained by the presence of an otherwise occult malignancy at screening, but it cannot be excluded that the development of some cancers may be associated with a state of low serum cholesterol.