Water Aerobic exercises hydroids; are practicable in different forms; such as running; jumping;walking and; which each are followed by exclusive results.The subjects were 30 untrained (junior high school) girl average age of (11-14) which wrerdivided in two experimental and control groups and on each group; aerobic power; bodycomposition; weight and 540m run time has been pretestedand post tested. The experimentalgroup has commenced their running plan; in water with depth of 70% of their height and thisplan has been peated 3 times per week and lasted 6 weeks. The running time in water startedfrom 20 minutes and in each session; 1 minute has been added to exercise time until the end; atthe final session the tested subjects were exercising in water for 37 minutes.The outoomes are:1) a significant (P<0.005) increase of absolute Vo2 max about 4.379 percent.2) a significant (P<0.018) decrease of weight about 1.74 percent.3) a significant (P<0.005) decrease subcatancons fat about 6.55 percent.4) a significant (P<0.005) decrease of 540 run time about 12.83 percent.