Professional organizations advocate universal access to medical care as a primary approach to improving health in the population.Access to medical services is critical to outcomes of acute processes managed in an inpatient hospital, the setting of most medical education, research, and training, but seems to be limited in its capacity to affect outcomes of outpatient care, the setting of most medical activities. Persistent and widening disparities in health according to socioeconomic status provide evidence of limitations of access to care. First, job classification, a measure of socioeconomic status, was a better predictor of cardiovascular death than cholesterol level, blood pressure, and smoking combined in employed London civil servants with universal access to the National Health Service. Second, disparities in health according to socioeconomic status widened between 1970 and 1980 in the United Kingdom despite universal access (similar trends were seen in the United States). Third, in the United States, noncompletion of high school is a greater risk factor than biological factors for development of many diseases, an association that is explained only in part by age, ethnicity, sex, or smoking status. Fourth, level of formal education predicted cardiovascular mortality better than random assignment to active drug or placebo over 3 years in a clinical trial that provides optimal access to care. Increased recognition of limitations of universal access by physicians and their professional societies may enhance efforts to improve the health of the population.