The purpose of this paper is (a) to present brief historical notes on the concept of race, (b) to define race in the context of evolutionary biology, (c) to quantify the extent of human genetic variation, (d) to estimate genetic differences within and between races, and (e) to comment on the implications of these concepts for racial differences in sport performance. Research shows that genetic variation in gene products and in the non-coding sequence of DNA is quite extensive in humans. Variation is found more frequently in non-coding DNA sequences than in coding exons, and while this variation does not influence the primary structure of the proteins, it may have considerable impact on gene expression. However, much of that genetic variation is shared by all human beings, and only about 10% is specific to races or populations within races. At this time, it is not possible to conclude satisfactorily the significance of these modest racial differences in genetic variation for racial differences in performance. It may turn out that this low level of genetic heterogeneity may have considerable implication for performance.