Bioelectrical impedance analysis (BIA) is a fast, easy to administer, and relatively inexpensive method of evaluating body composition. Due to the ease of operation, interest in using BIA to estimate percentage of body fat (%BF) has grown, especially in settings where body composition assessments are often performed without the benefit of properly-trained personnel (e.g., school districts). Extremely popular are the relatively new leg-to-leg bioelectrical impedance analysis (LBIA) devices that measure body composition as the individual stands on a bathroom-like scale. The LBIA method introduces a low level electrical current into the body and measures the lower-body impedance, or resistance, to the current flow. From impedance, fat-free mass and %BF can be estimated using equations developed for adults and children. This investigation examines the effect an acute bout of structured, moderately intense physical exercise in a field setting had on LBIA-estimated %BF in children. The primary finding of this investigation was that an acute after-school exercise program had a minimal effect on LBIA-determined %BF in children. (Contains 1 table and 1 figure.)