The effects of a 10 min, 5400 m ride, on plasma lipid and protein profile was studied in 9, two-year old male English horses. Blood samples were collected from all horses before the ride, at the 5th and 10th min of the ride and at 1/2, 6. 12 and 24 hours after the ride. Compared to the resting values, although slight increases in plasma triglyceride, total protein, albumin, creatinine and urea levels and slight decreases in cholesterol and total bilirubin levels were found during exercise, these changes were not considered significant statistically.