This study investigated benefits of 26 weeks of moderate aerobic exercise for women 70 years or older. Sixteen healthy women with a mean age of 72.0 years were randomized into exercise (n = 10) and control groups (n = 6). The exercise group walked on a treadmill 3 times per week for 20 min, at 70% of maximum heart rate. Oxygen uptake VO2max expressed in l/min and ml.kg-1.min-1, total exercise time on the treadmill (TET), maximum heart rate (HRmax) and body mass index (BMI) were measured at baseline and 6 months. Two-way repeated measures analysis of variance (ANOVA) determined the effect of exercise intervention. Both measures of VO2max in addition to TET were significantly improved by the moderate training program, compared to the control group. VO2max in the exercise group increased by +/- 6.6% (S.E. 2.9) measured in l/min and 8.4% (S.E. 3.2) measured in ml.kg-1.min-1. TET increased by 25.4% (S.E. 4.9) in the exercise group. The ANOVA was unable to detect significance between the exercise and control groups for HRmax or BMI. All exercising subjects finished the program, apparently tolerating the intervention. The results indicate that healthy women over the age of 70 years can increase fitness measures with a moderate training program.