High Intensity Interval Training (HIIT) is a phrase quickly becoming popularized through current research due to the physical and physiological success this method of training has proven to yield in both untrained and trained individuals. There is no set definition used to describe HIIT, but it typically refers to repeated bouts of fairly brief intermittent exercise. A great deal of research outlines the benefits associated with utilizing HIIT in untrained and recreationally trained individuals. However, research on the effect HIIT has or could possibly have on the well-trained endurance athlete is limited, specifically in the sport of rowing. The purpose of this study was to analyze the effect of HIIT on VO2 peak and performance in trained rowers when compared to traditional, endurance training. It was hypothesized that HIIT would be just as effective at improving VO2 peak and performance as the endurance training protocol in well-trained rowers. A total of 20 high school female rowers participated in the study (mean ± SD; age = 16 ± 1). Baseline testing was comprised of a 2000m time-trial test on the Concept IIc Rowing Ergometer and a maximal exercise test, which was also completed on the Concept IIc Ergometer, in order to determine VO2 peak. Subjects were randomly assigned to a HIIT or endurance group for four weeks of intervention. Three days/week the HIIT group completed a 6 by 30second repeated Wingate protocol on the Concept II Ergometer at or above 100% VO2 peak, in which each 30s maximal effort was immediately followed by an active recovery of four-minutes. The endurance group completed 30 minutes of sub-maximal rowing at 65% of VO2 peak three days/week. After four weeks of intervention, post-testing took place, which was identical to baseline testing. Results from this study suggest HIIT was just as effective as endurance training at improving 2k time (mean ± SD; HIIT: 498.7 ± 23.1; Endurance: 497.5 ± 17.6). There were no significant within or between group differences in VO2 peak post-intervention (mean ± SD; HIIT: 44.8 ± 4.0; Endurance: 45.8 ± 5.6). The current study suggests four-weeks of HIIT training can yield similar adaptations in performance when compared to endurance training.