The Seated Medicine Ball Throw (SMBT) is low-risk, easy to perform, requires minimal equipment, and is a valid measure of upper body explosiveness. The Ballistic Ball™ (BB) medicine ball contains inertial sensors which estimate peak velocity, and transmits these values to an iPad™ app via Bluetooth™. This method of gathering data may be superior to using horizontal distance as there is less chance of confounding factors and it is easier to administer. The objective of this study was to evaluate the reliability of the BB peak velocity measurement in the SMBT. Twenty healthy, rested, recreationally-active, undergraduate students volunteered to participate in this study. After a standard dynamic warm-up, subjects were taught proper throwing technique. For familiarization, subjects performed repeated SMBTs with a 10 lb BB until horizontal distance thrown for 3 consecutive trials was within 0.25m. After 20 minutes of rest, subjects repeated the warm-up protocol, then performed 6 trials with the same 10 lb BB for which peak velocity was recorded. The test-retest reliability of these 6 trials was analyzed using intraclass correlations (ICC). The ICCs between consecutive trials ranged from 0.94 to 0.98. Peak velocity for trials 1-6 were: 3.85±1.14 m/s, 3.86±1.06 m/s, 3.94±1.22 m/s, 3.85±1.13 m/s, 3.95±1.21 m/s, 3.92±1.20 m/s, respectively. The high ICC values suggest excellent reliability of the peak velocity measurement from the BB device. The BB peak velocity as assessed during a SMBT is a reliable method for assessment of upper body explosiveness.