The purpose of this study was to compare the physiologic effects of a program of combined running and weight training (RUN-CWT) with a program of circuit weight training (CWT). Thirty-six females (± age=35.7 yr) and 41 males (± age=36.1 yr) were randomly assigned to RUN-CWT, CWT, and control groups. The training groups participated in 12-wk programs, 3 d-wk−1. Three circuits of 10 weight-training exercises were completed with 12–15 repetitions performed in 30 s at 40% of one-repetition maximum at each station. The 30-min RUN-CWT program included 30 s of running on an indoor track following each CWT station, whereas the 22.5-min CWT program included a 15-s rest period between stations. The RUN-CWT groups had a significant (+17%) increase in Vo2max(females 30.5–35.7 ml-kg−1-min−1and males 39.7–46.3 ml-kg−1-min−1) and strength (females +24% and males +21%), and a significant decrease in body fat percentage (females —3.2% and males — 4.1%). The CWT groups also increased significantly in VO2max( + 12%) and strength (+17%) and decreased in body fat (-3.0%). The controls did not change significantly in any variable. Statistically, one training program was not shown to be superior to the other; thus, both programs of RUN-CWT and CWT were effective in improving measures of physical fitness.