The purpose of this study was to examine the effects of differing L-citrulline supplementation schemes on high-intensity, upper-body resistance exercise performance and rating of perceived exertion (RPE) as well as examine the placebo effect of supplementation. In this study, 10 subjects (6 male, 4 female) completed four sessions which included completing 3 sets on a seated chest press. Subjects also completed a familiarization and control session with no supplement intervention. The independent variables were the varying supplementation patterns of each intervention. The dependent variables were the maximal number of repetitions and RPE. After familiarization and the control trial, subjects were randomized into supplementation of citrulline or the placebo. The supplementation protocol was a seven-day supplementation with two data collection sessions occurring on the first and seventh day. The subjects completed an identical protocol after a 7-day washout period with the other intervention. It was hypothesized that citrulline supplementation would increase the maximal number of repetitions performed in the first set and decrease the RPE after each set (with respect to both the control and placebo). It was hypothesized that the placebo would have an ergogenic effect on both the maximal of number repetitions and RPE; however, there would also be a significant difference between the citrulline results and the placebo. Lastly, it was hypothesized the chronic citrulline supplementation would be more ergogenic than acute supplementation of citrulline. The average maximal number of repetitions for the chronic citrulline was 18.2 repetitions and was 15.4 repetitions for the chronic placebo; a 16.67% increase. This study found a 7.69% improvement in the average maximal number of repetitions between the acute and chronic citrulline trials. There was a 13.34% improvement in average RPE (Set 3) between the acute and chronic citrulline trials. Data concluded that (1) citrulline supplementation, both acute and chronic, significantly (p < 0.05) increases maximal upper-body resistance training performance with respect to both placebo supplementation and control trials, (2) chronic citrulline supplementation increases average maximal number of repetitions (18.2 repetitions) significantly (p [0.04] < 0.05) more than acute citrulline supplementation (15.5), (3) citrulline supplementation, both acute and chronic, significantly (p < 0.05) improves subjective ratings of perceived exertion (RPE) with respect to both placebo supplementation and control trials, and (4) chronic citrulline supplementation significantly (p [0.033] < 0.05) improves RPE more so than acute citrulline supplementation.