This study extends current understanding of caffeine intake on the menstrual and premenstrual syndrome; in particular, the association between PMS and caffeine consumption in 83 undergraduate female students--34 PMS and 49 controls. Participants between the ages of 18 and 26 were recruited from psychology courses at the University of Maryland. Diagnoses of PMS were assigned based on a 30% increase across two consecutive cycles of prospective symptom ratings online. Participants were screened using the PHQ for the following exclusion criteria: pregnancy, caffeine sensitivity, and any diagnosis of psychiatric disorder within the past 6 months. It was hypothesized that PMS sufferers would consume more caffeine across the entire menstrual cycle. The result of the present study showed that caffeine intake was higher during the follicular phase than during the luteal phase for both diagnostic groups. However, there was no significant difference between the two groups in caffeine intake.