Research diagnostic criteria for premenstrual tension syndrome (PMTS) are developed using data collected from a study of 42 women who were suffering from severe PMTS but were well at other times. Two specific scales are also devised for rating the severity of PMTS, a 36-item self-report questionnaire and a 10-item scale for use by therapist/researcher. It is proposed that after further evaluation and validation, these instruments may permit more useful comparisons of data on the etiology and treatment of this disorder.