Significance: The number of U.S. marathon runners has increased exponentially since 1976, with women today comprising 40% of all finishers. Studies that relate marathon performance time (MPT) to training regimens have been conducted using male subjects; however few studies have been conducted using female marathoners. The purpose of this study was to determine the correlation between marathon performance time (MPT) and age, physical characteristics (height, weight, BMI), past running experience (total marathons completed, marathons completed per year, number of years running distances greater than 5 miles), and various training indices (duration, intensity, frequency). Design: One hundred fifty female marathon runners were randomly selected to participate. Subjects ranged in age from 25 to 50 and had completed at least one marathon. Subjects were randomly selected from the computer files of the International Race Network. Questionnaires were mailed to 150 female subjects. Eighty-two percent (n = 123) of the questionnaires were completed and returned within 6 weeks. Data were analyzed using descriptive statistics, Pearson product correlations, and stepwise regression analysis. Results: Age, physical characteristics, and past running experience showed little correlation to MPT. Intensity of training, specifically minute per mile pace for distances of 10-15 miles (r = 0.83), minute per mile pace for distances of 5-10 miles (r = 0.81), and fastest mile time (r = 0.76) had the highest correlations to MPT. These findings indicate that intensity of training was the most important factor for ensuring proper overload when preparing for a marathon. In this study, intensity of training has been shown to be positively correlated to marathon performance time for female runners. These results are similar to those found for male marathoners.Keyword(s): adult physical activity/fitness, exercise/fitness/physical activity