There are limited published data in the bovine species on blood biological variables in response to intense work or after significant physical exertion. Lidia cattle, in addition to their exercise components, have some behavioral agonistic features that make them more susceptible to stress. The bullfight involves stress and exercise so intense that it causes significant changes in some metabolic variables. The study objective was to evaluate changes in blood biological variables in response to intense exercise and stress. After the fight in the arena, and once the bulls were dead (n = 438), blood samples were taken, and some biochemical and hormonal variables were determined in venous blood. A descriptive analysis was performed using the Statistica 8.0. computer program. The mean ( s.d.) results obtained were: total protein (85.8 10.8 g/dL), albumin (3.74 4.3 g/dL), triglycerides (39.65 0.16 mg/dL), cholesterol (2.44 0.03 mmol/L), glucose (22.2 9.6 mmol/L), uric acid (340 80 mol/L), creatinine (236.9 0.4 mol/L), urea (5.93 1.27 mmol/L), LDH (2828 1975 IU/L), CK (6729 10,931 IU/L), AST (495 462 IU/L), ALP (90 33 IU/L), GGT (50 34 IU/L), ALT (59 35 IU/L), cortisol (117.5 46.6 nmol/L), and testosterone (20.2 23.8 nmol/L). Most of the measured variables clearly increased; thus, we found severe hyperglycemia and increases in LDH, AST, GGT, and ALT enzymes, particularly in CK. The increases in all these variables are justified by the mobilization of energy sources, tissue/muscle damage, and dehydration due to continued stress and intense exercise.