The relationship between gastrointestinal (GI) symptoms and uterine cramping pain at menses, controlling for affective states and prostaglandin synthesis inhibitor use, was examined. A total of 53 women completed a daily diary of symptoms, stool characteristics, and medication use for three consecutive menstrual cycles. There were significant across-women and within-woman relationships between stomach pain, nausea, and uterine cramping pain, but not between cramping pain and constipation, diarrhea, or stool characteristics. These results support the presence of a similar mechanism in the generation of distressing GI symptoms and uterine cramping pain at menses.