Eighty-two consecutive cases of women who sought help for premenstrual syndrome (PMS) at the PMS clinic, University Hospital of Umeå, Sweden were studied. The presence of PMS was diagnosed by prospective daily rating of symptoms. The women also completed a modified Moos menstrual distress questionnaire (MDQ)- and an Eysenck Personality Inventory (EPI). Two patients were excluded because of poor daily ratings. The remaining 80 women were divided after the diagnostic procedure into three groups: group I with pure PMS, group II called the premenstrual aggravation group and group III where cyclicity of symptoms could not be ascertained. Several demographic factors concerning marital status, education, employment, and previous medical, psychiatric and PMS history were studied, as well as menstrual problems per se. No significant differences between the three subgroups were found in the analysis of the demographic factors. The only difference was that the pure PMS group contained a significantly smaller number of patients with pathologically high scores for neuroticism in the EPI, together with a smaller number of patients with a psychiatric history.