Daily ratings of depression, pain, and menstrual blood loss, as well as past history of treated depression, were analyzed in 210 women attending a Premenstrual Syndrome Clinic.Severity and duration of perimenstrual depression was strongly associated with the severity of premenstrual and menstrual pain, raising the possibility of a causal relationship. It is not yet clear whether the occurrence of depression alters a woman's perception of pain, pain aggravates a tendency to perimenstrual depression, or some common factor aggravates both. A relationship between depression and subjective ratings of blood loss was also observed but was less marked than the relationship with pain. Both relationships had been reported in an earlier study using retrospective ratings. A relationship between past history of treated depression and severity and timing of current perimenstrual depression, observed previously, was not found in this study. This discrepancy was not due to differences between retrospective and prospective methods of assessment, but may have partly resulted from differences in the reporting of premenstrual pain in the two studies. Further studies of this association should control for the confounding effect of pain.