The burgeoning research in psychosomatic medicine requires quantitative measures reflecting important biological, psychological, and social variables. The Seriousness of Illness Rating Scale (SIRS), although twenty years old, is currently utilized in psychosomatic research as an index of illness seriousness. In light of medical advances during the past two decades, an expansion and re-standardization of the SIRS appeared warranted. Forty-six medical students, residents, and faculty rated the seriousness of 137 disease items. High inter-rater reliability was demonstrated by a concordance coefficient of 0.716 and overwhelming agreement on relative disease item rankings between the three medical groups. Thus, the Seriousness of Illness Rating Scale-Revised (SIRS-R) is an ordinal level scale which reliably measures current views on illness seriousness and can be easily employed in multivariate psychosomatic research.