having an ideal body shape is the desire of everyone, both young and old. The purpose of this study was to determine (1) the effect of block circuit training on aerobic fitness and body fat percentage, (2) the effect of non-block circuit training on aerobic fitness and body fat percentage, and (3) differences in the effect of exercise on block and non-circuit training block against aerobic fitness and body fat percentage. This research is an experimental research and as a result of this made use of pre-test post-test design two groups design as its research design method. The population in this study were 57 members of fat loss at GOR UNY Fitness Center. Purposive random sampling method was used and as a result of this, 20 people were sampled. Rockport test (1.6 KM) and body fat percentage with a scale of Bioelectrical Impedance Analysis Omron (BIA) were used as instruments. The result of this research showed that the circuit training between block and nonblock has a significant effect on aerobic fitness and body fat percentage and that differences in the effect of circuit training between blocks and non-blocks is more influential on aerobic fitness than the percentage of body fat.