One hundred eight patients with muscle contraction headaches completed a double-blind, randomized, parallel trial in which they took either ibuprofen 400 mg, ibuprofen 800 mg, a spirin 650 mg, or placebo for four successive headaches. Acetaminophen was allowed as a rescue analgesic. Intensity of headache pain was recorded pretreatment and three hours posttreatment. A Pain Intensity Difference (PID) score was calculated from the difference. Patients on ibuprofen (both doses) and aspirin had significantly lower pain scores and higher PID scores at three-hour follow-up than did patients on placebo. Physician's global assessment indicated that both doses of ibuprofen were significantly superior to placebo; aspirin was not. The highest number of side effects occurred with aspirin (26 complaints), followed by placebo (11), ibuprofen 400 mg (3), and ibuprofen 800 mg (2); all were minor. These results suggest that, for the treatment of muscle contraction headache, ibuprofen is significantly more effective than placebo and at least as effective as aspirin.