The medically underserved present unique challenges to primary care pr
actitioners. Sociocultural and financial barriers of the underserved i
mpede access to necessary care; the prevalence and severity of disease
s in the underserved population vary from those of the general populat
ion; the institution of preventive-care measures can be especially pro
blematic; and the doctor-patient relationship is uncommonly complex. T
his article reviews current thinking about the causes of unequal healt
h, the effects of unequal health care, and the special opportunities f
or disease prevention among the socioeconomically disadvantaged people
in the US. Sensitivity to these and other issues can enhance primary
care practitioners' efforts to improve care of the underserved now, pe
nding future political consensus about universal health insurance.