This study examined the effects of aspartate supplementation (ASP) on plasma ammonia concentrations ([${{\text{NH}}_4}^{+}$]) during and after a resistance training workout (RTW). Twelve male weight trainers were randomly administered ASP or vitamin C in a crossover, double blind protocol, each trial separated by 1 wk. ASP and vitamin C were given over a 2-hr period beginning 5 hr prior to the RTW. The RTW consisted of bench, incline, shoulder, and triceps presses, and biceps curls at 70% of one repetition maximum (1-RM). After the RTW a bench press test (BPT) to failure at 65% of 1-RM was used to assess performance. [${{\text{NH}}_4}^{+}$] was determined preexercise, 20 and 40 min midworkout, immediately postexercise, and 15 min postexercise. Treatment-by-time ANOVAs, paired t tests, and contrast comparisons were used to identify mean differences. No significant differences were observed between treatments for [${{\text{NH}}_4}^{+}$] or BPT. [${{\text{NH}}_4}^{+}$] increased significantly from Pre to immediately postexercise for both the ASP and vitamin C trials. Acute ASP supplementation does not reduce [${{\text{NH}}_4}^{+}$] during and after a high intensity RTW in weight trained subjects.