Literature on health disparities documents variations in clinical decision making by patient characteristics, physician attributes, and between healthcare systems. Using data from a vignette-based factorial experiment of 256 primary care providers, we examine the cognitive basis of disparities in the diagnosis and treatment of coronary heart disease (CHD). To determine whether previously observed disparities are due to physicians: (1) not fully considering CHD for certain patients or (2) considering CHD but then discounting it, half of physicians were explicitly directed to consider a CHD diagnosis. Relative to their unprimed counterparts, primed physicians were more likely to order CHD-related tests and prescriptions. However, main effects for patient gender and age remained, suggesting that physicians treated these demographic variables as diagnostic features amounting to lower risk of CHD for these patients. This finding suggests potential for physician appeals to perceived base rates to contribute to the further reification of socially constructed health statistics.