The purpose of this study was to investigate the effect of same-day strength training on bat swing velocity of male collegiate baseball players. Sixteen male baseball players engaged in a preseason strength training program designed by the team's strength and conditioning coach. All subjects were tested for bat swing peak velocity immediately prior to ball impact for a non lifting day (NLD) by recording 10 swings with 30 seconds of rest in between swings. The next day, a lifting day (LD), all subjects tested on the NLD were tested four to six hours after the morning lifting session with the same amount of swings and rest. Six Vicon MX13+ infrared cameras (Vicon-Colorado, Centennial, Colorado), running at 400 Hz, were placed around the swinging area using Nexus 1.2 imaging software to download and determine bat swing peak velocity immediately prior to ball impact. The average of the top six bat swing peak velocity test results, for each subject, was compared to measures taken on the NLD and LD. A matched t-test revealed a significant difference in bat swing peak velocity between a NLD and a LD. A mean bat swing difference between NLD (69.18) and LD (70.86) of 1.68 was statistically different at better than the .05 level [p =.021]. This study suggests that male collegiate baseball players should be able to engage in a designed strength training program with a positive effect, and without any negative effect, on bat swing peak velocity when a strength training session is scheduled on the same day as a baseball competition.