We examined the use of a six-item linear analog scoring system comprised of three somatic and three mood-related items for the documentation of premenstrual syndrome. One hundred forty women with suspected premenstrual syndrome completed the linear analog scale, as well as the validated 36-item Self-Rating Scale for Premenstrual Tension Syndrome and the 35-item Prospective Record of the Impact and Severity of Menstrual Symptomatology calendar. Ninety patients and 20 normal control subjects completed two cycles of records. With use of clinical criteria and self-rating scale scores as the "gold standard," 73 patients were diagnosed as having premenstrual syndrome. Linear analog scale scores were highly correlated with both self-rating scale scores (r = 0.72, day 9; r = .66, day 27; p = 0.001) and prospective record scores (r = 0.74, day 9; r = 0.60, day 27; p = 0.001). Our results suggest that the linear analog scale may be a useful clinical tool in the study of premenstrual syndrome. Because of its simplicity, the linear analog scale may increase patient compliance. Because of its sensitivity to detect changes in symptom severity throughout the menstrual cycle, it may prove useful in evaluating the effects of therapy for premenstrual syndrome.