A growing body of evidence supports or rejects preventive interventions in asymptomatic adults. Thus, counseling for smoking cessation and some immunizations have been shown to be cost-effective. Evidence supports screening for body weight (obesity), hypertension, hyperlipidemia, cervical cancer, colorectal cancer and breast cancer. Screening for lung, pancreatic and ovarian cancer has no effect on outcome and should not be performed. Controversial preventive interventions include general screening for diabetes mellitus in the young adult, thyroid disorders and prostate cancer. Physicians should be aware of a possible hidden agenda in patients presenting for a check-up.