Physicians may not comply with all of the preventive medicine recommendations issued by recognized medical consensus groups. Compliance with recommendations for mammography, Papanicolaou tests and smoking cessation counseling is particularly important because of the potential to save lives. Compliance failure rates are often underestimated, in part because of misconceptions about the nature of physician compliance. An understanding of the difficulty in accurately estimating compliance and an awareness of the factors that affect compliance are fundamental to improving the delivery of preventive services.