Abstract: This research has an objective of evaluate the serum biochemical concentrations of Creatine Kinase (CK), Lactic Dehydrogenase (LDH), Aspartate Aminotransferase (AST), Gamma-Glutamyltransferase (GGT), creatinine, urea, albumin and calcium in Pantaneiro horses created extensively in the Pantanal Region of Brazil. Blood samples from a total of 52 male and female horses were collected and divided into 5 groups according to the age of the animals. The mean values of the serum concentrations were: CK 221.3 U/L±75.22-287.8 U/L±110.67; LDH 899 U/L±263.8-1264 U/L±83.5; AST 220 U/L-282±54.01 U/L±30.78; GGT15.3 U/L±3.91-30.6 U/L±10.25; creatinine 0.85 mg/dL±0.13 the 1.20 mg/dL±0.17; urea 32-44.5±5.83 mg/dL±7.04; albumin 2.80 g/dL±0:28-2.43 g/ dL±00.46; calcium 10.75 mg/dL±1.1-11.8 mg/dL±2.62. All groups showed increased values for CK and GGT and decreased values for serum calcium compared from other references from the specie. There was found a wide variation in the LDH values. The age group influenced the serum results of creatinine, albumin and calcium.