The TCR repertoire of human CD8+ peripheral blood lymphocytes has been determined using MoAbs to the Vβ2, 3,5.1,5.2/5.3,6.7,8,12 and 19(17) Vβ gene families. The CD8 T cell repertoire for Vβ2 and Vβ3 is shown to be skewed, with an excess of individuals having higher values than are consistent with a normal distribution. A significant majority of these individuals are over the age of 40. High values of Vβ CD8+ cells were found for each Vβ family studied except for 6.7a. Individual high values are stable for at least 12 months. In addition, the total percentage of CD4 and CD8 cells reacting with this panel of reagents was determined. There is a significant excess of Vβ+ CD4+ cells (33%) over CD8+Vβ+ cells (21·9%). Thus the human CD8 Vβ repertoire differs from the human CD4 repertoire in a number of important ways.