Dietary inorganic nitrate (NO3-) supplementation has been shown to improve maximal muscle power and exercise tolerance at high, but not low contraction velocities during lower body exercise (Coggan et al, 2014; Bailey et al, 2015). Supplementation also improves upper body performance (Peeling et al, 2015), however, it remains unclear whether NO3- supplementation improves muscle power or exercise tolerance during ‘all-out’ upper body exercise. We tested the hypotheses that during all-out bench press exercise, acute NO3- supplementation would improve performance by: i) increasing total work ii) prolonging time to exhaustion iii) increasing mean power. Eight men, age 26.4±3.1 years; height 1.79±0.06 m; mass 81.5±12.8 kg (mean±SD), consented to participate in a randomised, double-blind cross-over study, which had University ethical approval and followed the principles laid out by the Declaration of Helsinki. Volunteers responded to poster advertisements and were able to withdraw from the study at any stage without reason. During visits, participants arrived to the laboratory in the morning following an overnight fast. Diet was replicated between trials and foods high in NO3- were avoided. Following thorough familiarisation, participants returned to the laboratory on two occasions, separated by a minimum of seven days, during which they were instructed to perform bench press exercise (Smith machine) as fast as they could at 40% 1RM (one repetition maximum), and to continue the protocol to maximal volitional exhaustion. During the two experimental visits participants consumed either beetroot juice (BR; 13 mmol NO3-) or placebo (PL; NO3- depleted BR) (Beet It Sport, James White Drinks, UK) 2.5 hours before exercise. Blood pressure (BP) was measured using an automated sphygmomanometer (Dinamap 400 ProV) before ingestion, and again before exercise. Bench press performance was assessed from video analysis (30Hz) for time to exhaustion (s), total work (kJ), and mean power (W). Student’s t-tests were used to identify differences between BR and PL and a two-way ANOVA for BP (SPSS 22). There was no main effect of supplement on BP (120±8/70±6 vs.119±10/70±6 mmHg, BR vs. PL respectively), and there was no interaction effect for condition over time. There was no difference in time to exhaustion between BR (46.7 ± 6.4) and PL (45.7 ± 5.5 s), however, both total work performed (BR: 8.8 ± 2.5; PL: 8.2 ± 2.5 kJ; P<0.05) and mean power (BR: 188 ± 56; PL: 179 ± 58 W; P<0.01) were greater with BR compared to PL. The present results show increased total work and mean power with BR during all-out, upper body exercise, without any change in time to exhaustion. The physiological explanation for these findings remains unclear, but may relate to improvements in local muscle oxygen delivery, perfusion or extraction.