Objective To determine the effects of a 12-week aerobic exercise program on brachial-ankle pulse wave velocity ( baPWV) in sedentary and under-exercised healthy older adults. Methods A total of 35 sedentary and unfit but healthy older adults with mean age of 74.7 years were randomly assigned to a progressively increased intensity aerobic exercise group ( n = 17) or a control group ( n = 18). The exercise group performed aerobic exercise 3 times each week for 12 weeks. The control group didn't participate in the exercise program. Heart rate,blood pressure and baPWV were evaluated at admission to the aerobic exercise program and at the end of the 12 weeks in both groups. Results The mean baPWV in the aerobic exercise group decreased from 15.88 m/s to 14.62 m/s after exercise, a significant reduction. Blood pressure in the exercise group showed a decrease which was not significant. No significant improvement was identified in the control group. Conclusions Only 12 weeks of aerobic exercise with progressively increased intensity can improve arterial elasticity in sedentary and unfit older adults.