Aspirin and other NSAIDs have a potential role in the primary and secondary prevention of many common diseases associated with aging, including the top two causes of mortality in the United States-cardiovascular disease and cancer. These agents may be beneficial in the management of Alzheimer's disease,other forms of dementia, and Parkinson's. disease. Because men with prostate cancer or precancer are likely to present with coexisting conditions that would be affected by systemic aspirin, NSAID, or other COX-2 inhibitor therapies, it is important to consider any possible preventive studies or future clinical recommendations of aspirin or NSAIDs for prostate cancer within the context of these comorbid conditions. Aspirin or nonaspirin NSAIDs may be appropriate prevention therapy for patients at high risk of prostate cancer, myocardial infarction, Parkinson's disease, Alzheimer's disease, lung cancer, or colorectal cancer, but low risk for gastrointestinal complications or stroke. Further quantitative comparative studies of the risks and benefits of these common comorbidities in older Americans, with special attention to dose and duration parameters, are warranted.