Nineteen selected interspecific peanut lines with resistance to leaf spot [Cercospora arachidicola Hori and/or Cercosporidium personatum (Berk, and Curt.) Deighton] were field tested 3 yr for disease reaction and productivity with and without foliar fungicide protection. Measurements included severity ratings of leaf spot every 2 wk based on the Florida leaf spot disease rating scale, and pod yield. Area under disease progress curves (AUDPC) and pod yield losses were calculated. Differences among the interspecific lines in AUDPC values were significant, and one line had values equal to or lower than that of Southern Runner. One-half of the lines were equal in yield (P=0.01) to Southern Runner. Yields among lines averaged 1 to 50% higher with, as compared to without, chlorothalonil application. Yield losses of individual entries varied significantly from 1 yr to another and incongruous with the AUDPC pattern. Correlations between the AUDPC and yield loss were significant (P=0.01) for the 1989 and 1990, but not for the 1988 data. Results of the study indicate that resistance to both C. arachidicola and personatum were incorporated from the wild species parents into productive, runner-type breeding lines, and that the resistance to personatum was equal to or better than that of Southern Runner. Additional effort will be required to transfer levels of leaf spot resistance observed in the wild species parents into successful cultivars.