Much historical research on race, intelligence, and health was racist, unethical, and ineffective. The concepts of race and ethnicity are difficult to define but continue to be applied to the study of the health of immigrant and ethnic minority groups in the hope of advancing understanding of causes of disease. While a morass of associations has been generated, race and ethnicity in health research have seldom given fundamental new understanding of disease. Most such research is “black box epidemiology.” Researchers have not overcome the many conceptual and technical problems of research into ethnicity and health. By emphasising the negative aspects of the health of ethnic minority groups, research may have damaged their social standing and deflected attention from their health priorities. Unless researchers recognise the difficulties with research into ethnicity and health and correct its weaknesses, 20th century research in this subject may suffer the same ignominious fate as that of race science in the 19th century.