The interruption of daily consumption of caffeine-containing beverages can cause headache and other symptoms within 8 hours. Resumption of caffeine alleviates these symptoms. Surgical patients routinely fast preoperatively and may have postoperative symptoms from caffeine withdrawal. In the current study, we determined whether perioperative caffeine consumption altered the incidence of postoperative headache. After institutional approval of the study design, 233 surgical outpatients were surveyed about history of headaches, caffeine consumption, and the presence and severity of headaches postoperatively. Of the 233 patients, 190 (82%) drank caffeinated beverages daily (mean daily consumption, 290 mg of caffeine). Postoperative headaches occurred in 22% of patients who routinely drank caffeinated beverages but in only 7% of those who did not (P < 0.03). Other factors associated with postoperative headaches included a history of frequent headaches (P < 0.0001), age of 50 years or younger (P < 0.002), and amount of daily caffeine ingested (P < 0.01). Among daily caffeine drinkers, those who drank caffeinated beverages on the day of the surgical procedure had a lower incidence of postoperative headaches than did those who abstained (17% versus 28%; P < 0.04). Postoperative headaches may be related to several factors. Perioperative intake of caffeine altered postoperative well-being. Caffeine given preoperatively may limit postoperative withdrawal headaches among the millions of daily drinkers of caffeinated beverages. A randomized, prospective, and blinded trial to test this hypothesis is warranted.