A variety of instruments have been used in an attempt to operationalize DSM-IV criteria for premenstrual dysphoric disorder (PMDD) and to understand clinically significant premenstrual syndrome (PMS). The objectives of this research were to devise a simple user friendly screening tool to identify women who suffer from severe PMS/PMDD and who are likely to benefit from treatment. Five hundred and nineteen women, between the ages of 18 and 55 yrs, who were seen at a primary care facility completed "The Premenstrual Symptoms Screening tool" (PSST). The PSST reflects and 'translates' categorical DSM-IV criteria into a rating scale with degrees of severity. The results are in line with reported prevalence rates from several recent large prospective studies. We believe that the PSST applies a necessary degree of measure of severity and impact of premenstrual symptoms, establishes quickly if women qualify for PMDD, and is less time consuming and more practical than two cycles of prospective charting. This fast simple tool is an effective screening tool and an important starting point for further assessment.