The purpose of this study was to investig;lte effects of aerobic exercise in water and on land on obesity index (BMI, body mass index; BF, % body fat; WHR, waist hip ratio) and blood lipid proilles (TG, triglyceride; TC, total cholesterol; HDL, high density lipoprotein; IDL, low density lipoprotein) in young rrv:n Twenty volunteers were placed in two groups; i) Land (walking on land, n=lO, 2O.10±0.99 yrs, 173.70±4.00 CIIl, 75.47±3.93 kg) or ii) Water (walking in water, n=lO, 2O.6O±0.97 yrs, 174.77±S.33 CIII, 76.92±4.55 kg). For 8 weeks, each subjects were participated in exercise (3 day Iweek, 50 minI day) with same exercise intensity (the intensity was gradually increased from 5O±S% to 7O±S%) which were detennined individually by Karvonen formula. 1he depth of water was Xiphoid hight and water temperature was 29±1°C. Grcumferences of waist and hip were measured with measuring tape, and then waist-hip ratios (WHR) were calculated. After measuring heights, Bio-impedcmce method (In-body 4.0, Bio space, Korea) was used to determine percent body fat (%BF) and BMI (Body mass index)were calculated. Two way MANOV A and t-test were utilized to determine whether obesity index and blood ]lipid profiles varied between groups and period, and t-test was used as post-hoc. Significance was set at p<.ffi for all tests. BMI (p<.001) and %BF (p<.01) were significantly decreased after exercise in both groups, however, WHR were significantly decreased after exercise only in Water (p<.05). HDL-C were significantly decreased after exercise in both Land (p<.01) and Water (p<.ml), TC were significantly decreased after exercise only in Water (p<.05).whereas there were no significant differences in LDL-C and TG. In conclusion, walking in water is can be one of effective rrethod to improve obese and blood lipid level.