The purpose of the present study was to evaluate the effect of three different types of warm-up on swimming performance in NCAA Division I swimmers. Eight male and eight female swimmers utilized three warm-up protocols prior to performing 50-yard (45.72-meter) freestyle swim trials each trial in counterbalanced order and separated by 48 hours. The warm-up protocols consisted of: (1) no warm-up, (2) short warm-up (50-yards at 40% maximal effort and 50-yards at 90%), (3) regular warm-up (swimmers own pre-competition warm-up). Following the warm-up regimen, participants rested for three minutes and completed a 50-yard freestyle swim trial. Heart rate pre- and post- trial, diving distance, reaction time, post warm-up RPE, post 50-yard trial RPE, and stroke count were measured. Times for 50-yard swim were significantly (p = 0.03) different among warm-ups. Mean 50-yard time was significantly (p = 0.01) faster after regular warm-up (24.95 ± 1.53 sec) compared to short warm-up (25.26 ± 1.61 sec) and approached significance between no- and regular- warm-ups (p = 0.06); however, no significant difference was found between no- (25.19 ±1.54 sec) and short warm-ups (p = 0.59) on 50-yard time. Individual data indicated that 19% of participants performed their best 50-yard time after short warm-up, 37% after no-, and 44% after regular warm-up. Heart rate was significantly (p = 0.01) higher after regular warm-up (100 ± 13 b/min) compared to no warm-up (88 ± 18 b/min) and approached significance between short- and regular warm-ups (p = 0.07); however, no significant difference was observed between no- and short warm-ups (92 ± 19 b/min) (p = 0.32). RPE was significantly (p <0.001) lower after no warm-up (6.3 ± 0.5) compared to short warm-up (10.1 ± 1.7) and regular warm-up (12.1 ± 1.0). No significant difference was found in reaction time (p = 0.96), RPE post 50-yard time trial (p = 0.11), dive distance (p = 0.67), and stroke count (p = 0.23) among warm-ups. In conclusion, regular warm-up was better than short warm-ups to achieve the fastest mean 50-yard freestyle time but individuals differed in their response to different warm-ups.