This study was conducted to investigate the combined effects of VFA composition of rumen fluid and heat exposure on the blood constituents and acid-base balance in sheep. Each infusion group was subjected to either thermoneutral(20±2℃) or heat(30±2℃) environment for 4 days. Four adult Suffolk sheep fitted with a permanent ruminal cannula and a simple T-shaped duodenal cannula were used and infusion nutrients were examined by use of the continuous alimentation technique. A peristaltic pump was used to infuse the solutions of volatile fatty acid triglycerides(VFA-TG) consisting of 70 triacetin : 20 tripropionin : 10 tributyrin (low propionin division: LP) and 50 triacetin : 40 tripropionin : 10 tributyrin (high propionin division: HP) on the basis of energy and minerals into the rumen, and casein solution into the duodenum. The results obtained are summarized as follows: 1. Plasma glucose and insulin concentrations almost remained unchanged by the temperature treatment and the levels of VFA-TG solutions(LP and HP). Plasma lactate concentration increased(P$lt;0.05) during the heat exposure at the HP division, but was not affected by the levels of VFA-TG solutions. Plasma TG concentration increased(P$lt;0.01) during the heat exposure at the LP division probably due to the days of VFA-TG infusion rather than the heat stress. Plasma urine-N concentration tended to be higher under the heat exposure and increased in the HP than LP division. 2. During the heat exposure at the LP division, blood HCO₃-concentration almost did not exhibit clear changes, but blood Pco₂ tended to be decreased and blood pH tended to be increased (condition of respiratory alkalosis), and blood base excess concentration tended to be higher. 3. Blood Hb concentration tended to be lower in the LP division but remained unchanged by the temperature treatment in the HP division and was not affected by the levels of VFA-TG solutions. 4. Blood Na^+ concentration tended to be lower under the heat environment than the thermoneutral environment. Blood K^+ concentration remained unchanged by temperature and the levels of VFA-TG solutions. Blood Ca^(2+) concentration