The physiological and anthropometric characteristics of 23 non-elite women marathoners were studied. Ten of these women had never run a marathon before (novices) and 13 had run at least one marathon during the previous year (experienced). A comparison of characteristics of these two groups to each other and to elite women marathoners, as reported in the literature, disclosed no significant (p greater than 0.01) among the groups in age, % body fat, body weight, height, lean body mass or HR max. Significant differences (p less than 0.01) were noted, however, in VO2 max (45.8, 51.8, 59.1 ml.kg-1 min-1), VE max (76.3, 94.7, 108.9 L.min-1), and years of training (0.54, 2.06, 4.55 years) with the novice runners having the smallest values, the experienced runners having the next larger values, and the elite runners having the largest values. For our subjects, estimated percentage of body fat did not correlate with finish time, but VO2 max and finish time were significantly related (r = -0.72, p less than 0.01). This suggest that women marathon runners are similar in anthropometric measurements, and that improved performance is associated with higher aerobic capacity and years of training rather than with body dimensions.