Fluid restriction (FR) is commonly performed by athletes competing in weight-class sports, but the effects of fluid restriction on strength performance remain controversial. PURPOSE: To assess the effects of fluid restriction on muscular strength performance and fatigue. METHODS: Six participants (age 24 ± 2 y, body mass 87 ± 16 kg, ht 1.7 ± 0.1 m, body fat 18 ± 8%) randomly completed two experimental trials (euhydrated, EU, or FR). FR consisted of three days of graded decreases in fluid intake (1.5 L three days prior, 0.5 L two days prior, and 0.5 L the day prior to the trial). For each trial, participants cycled at 50 W for 10 minutes on cycle ergometer and completed a standardized dynamic warm-up. Participants then performed strength testing on an isokinetic dynamometer involving three repetitions of isometric knee flexion and extension at 70° and 90° and isokinetic contractions at 50 and 150°/sec. Next, a fatigue protocol of 30 maximal effort repetitions of isokinetic contractions at 180°/sec was performed, followed by the initial strength testing protocol. RESULTS: Body mass was reduced 1.9 ± 1.3% with FR compared to EU (mean difference: 1.8 ± 1.5 kg, P = 0.02). Urine specific gravity was increased following FR (1.025 ± 0.005) compared to EU (1.015 ± 0.008, P = 0.02). Perceived thirst was greater in the FR trial (grand mean, 3.4 ± 1.4) compared to the EU (grand mean, 7.2 ± 0.9, P <0.001) and rating of perceived exertion tended to be increased in the FR trial (16.1 ±1.8) compared to the EU (15.1 ± 1.9, P = 0.06, d = 0.87). Isometric strength was not different between conditions for extension at 70° (P = 0.44, ηp = 0.12) and 90° (P = 0.75, ηp = 0.02). Isokinetic strength was also not different between conditions at 50°/sec (EU 198.4 ± 50.7, FR 184.8 ± 38.7 Nm, P = 0.26, ηp = 0.24) and 150°/sec (EU 136.2 ± 35.8, FR 129.0 ± 41.9 Nm, P = 0.20, ηp = 0.31). During the fatigue protocol, total work completed was not different between conditions (EU 2656 ± 794, FR 2689 ± 902 Nm, P = 0.63), but, average power demonstrated a moderate-large effect (d = 0.71) for reduction in the FR condition (182.6 ± 65.0 W) compared to EU (206.5 ± 58.8 W, P = 0.14). CONCLUSIONS: These preliminary results suggest FR does not alter muscular strength or fatigue. However, perceptual strain (thirst, exertion) may be increased, requiring a greater effort to produce similar performance.