The effects of exercise conditioning on serum high density lipoprotein cholesterol (HDL-C) were studied using 20 members of a regular joggers club and other healthy non-member subjects of varying degrees of habitual physical activity (253 males and 391 females). Both the HDL-C and HDL-C/serum total cholesterol (TC) levels were significantly higher with the 20 regular joggers than with the sedentary controls matched for age, TC, serum triglycerides (TG) and weight index (WI). A significant correlation was found between HDL-C/TC and the exercise conditioning value obtained by using the results of the 12-min performance test as an index among the non-member subjects. In order to ascertain the relative significance of exercise conditioning in influencing HDL-C/TC, a multiple regression analysis was conducted using HDL-C/TC as the variable criterion. The results showed that TG affected HDL-C/TC the most among both males and females, while exercise conditioning affected it second among males and fourth among females.