We investigate whether ACE I/D gene polymorphism modulates anthropometric, cardiovascular, biochemical, OGTT, and fat oxidation responses to six weeks of short-term endurance training for untrained adults. Thirty-five untrained healthy individuals initially participated in the pre-test assessment and were screened for ACE I/D genotype. However, only seventeen participants completed three sessions of 45 minutes of endurance training every week for 4 weeks. Using two-way repeated measure ANOVA, the data were clustered among the three classes of ACE I/D genotype groups (II=3, ID=7, DD=7). Six weeks of endurance training resulted in increased the VO2 max (p=0.004), fat oxidation at 40% (p=0.028), 50% (p<0.001), 60% (p=0.011) and 70% (p<0.001) of VO2 max. A significant interaction effect between ACE and endurance training on the fat oxidation variables has been reported (F(18, 12)=2.701, p=0.042; Wilks’ Λ=0.039). The interaction observed showed that while the ID genotype group had a much higher fat oxidation score before endurance training, the II genotype group had the highest score after the training program. The present study found that short-term endurance training may be favorable for certain ACE I/D genotypes.