A BASIC microcomputer program (EPIPLOT) has been developed for predicting B and T cell antigenic sites in proteins from their primary structures. The program calculates and plots flexibility, hydrophilicity and antigenicity profiles using 13 different scales, chosen as those yielding the best predictions on proteins whose antigenic structures are known. T cell epitope prediction is based on published algorithms focused on amphiphilic structures and characteristic sequence patterns. The advantages of joint predictions in locating T cell antigenic sites are also discussed.