Fourteen female dental hygiene students (seven with episodic tension-type headache and seven who rarely or never experienced headache) wore an ambulatory electromyographic recorder and completed hourly subjective ratings of pain and negative affective states for six days while they carried out their normal daily activities. Three of the days were designated as high stress days by virtue of the fact that the students were required to take a major course examination or undergo a clinical evaluation on that day. The remaining three days were designated as low stress days by virtue of the fact that no unusual demands were made on the students, and they simply attended lectures as usual. All students showed significantly greater levels of electromyographic activity on the high stress days compared to the low stress days, but there was not a statistically significant difference between the headache and control groups. Headache group subjects reported significantly higher levels of pain compared to the control group, but their pain ratings did not differ between high and low stress days. Subjective ratings of negative affective states (anxiety, anger, sadness, and frustration) were significantly greater on high stress days compared to low stress days. Headache group subjects also exhibited a tendency to report higher levels of negative affective states than did control group subjects, but only in the case of frustration was the .05 level of statistical significance achieved.