Measurements were made through underwater weighing on the body compo-sition of 40 ordinary male students (Group 1) and another 50 majoring inphysical education (Group 2). Two simple equations were worked out forestimating the percentage of fat with figures of their skinfolds and circum-ferences. The average percentage of fat and lean body weight were found to be11.76% and 54.3 kg respectively for Group 1, and 9.83% and 59.7 kg forGroup 2. With F standing for the percentage of fat, t for triceps skinfold and s forsuprailiac skinfold, the equation derived from Group 1 was F=2.44523 +0.99009t + 0.46426s, and that derived from Group 2 was F=1.16283t+0.54526s--0.21702 In underwater weighing, the mean percentage of fat was 9.70 ? 2.19 with anormal amount of inhaled air and 9.24 ? 2.46 with a maximal amount. Theinsignificant difference indicates that the normal inhalation method is wor-kable and more acceptable to the subjects.