Clinical blood chemistry was studied on 13 Andalusian horses with laminitis. Ten healthy horses were used as controls. Blood samples were taken within the first 24 hr after the onset of the disease in Obel grade 3 before any type of treatment was given. No significant differences were observed in the number of red blood cells and white blood cells between Andalusian horses affected by laminitis and healthy animals. Significant decrease in the number of neutrophils and increased number of lymphocytes were noted. A significant increase in the enzymatic activity of CPK, LDH and AST in these animals strongly suggested the presence of muscular and hepatic disorders. The K ion increased, meeting with a slight acidosis. There was also an increase of glucose and total proteins. This fact may be a result of an excessive intake of carbohydrates (which could cause hyperglycaemia) and a diminution of the plasma volume, as a consequence of fluid movement as well as the sweating process (which could cause protein haemoconcentration).