A study was conducted to evaluate the temperament of beef cattle on grazing system regarding daily gain, ultrasound measures, and intake behavior. Twenty growing animals [Nellore; non-castrated males; 220 ± 3.73 kg initial body weight (BW); 10 ± 1 mo of age] on rotational stocking system (Brachiaria brizantha ‘Xaraés’) were used. Animals were evaluated for BW and temperament at the beginning of the trial period. Individual temperament scores were calculated by averaging animal chute score and exit score [adequate (ADQ) ≤ 3; or excitable (EXC) > 3]. Animals were ranked by BW and assigned to receive (n = 10) or not (control = CON; n = 10) a supplementation treatment (SUP; 0.6% of BW; corn, urea and mineral salt). BW were measured on d 0 and d 84 to determine the total gain (TG) and average daily gain (ADG). Hip height (HH) and ultrasound evaluations (ribeye area; backfat thickness) were carried out on d 0 and 84. Intake behavior evaluations were obtained via direct observation (8 d; 24-h per day) with an interval of 15 min between observations (time of grazing, rumination, resting, and drinking water). Data were analyzed with PROC MIXED in SAS with fixed effects of temperament, treatment and the resultant interaction. No interaction was significant. ADQ animals had greater final BW (P = 0.01) and HH (P = 0.01) than EXC animals (310.78 vs. 273.06 kg for BW; 1.36 vs. 1.32 m for HH, for ADQ and EXC animals, respectively). SUP treatment had greater final BW (P = 0.04), TG (P < 0.01), ADG (P < 0.01), final ribeye area (P < 0.01), and HH (P = 0.03) than CON treatment (305.80 vs. 278.04 kg for BW; 79.60 vs. 57.43 kg for TG; 0.95 vs. 0.69 kg for ADG; 37.25 vs. 30.84 cm² for ribeye area; 1.35 vs. 1.32 m for HH, for SUP and CON treatments, respectively). For intake behavior outcomes, ADQ animals had greater time of rumination (P = 0.01) than EXC animals (456.30 vs. 440.31 min, for ADQ and EXC animals, respectively). In conclusion, some characteristics of performance and intake behavior are associated with temperament and it is independent of differences in supplementation treatment in Nellore cattle. Supported by FAPESP#2014/07406–5