Sixty-eight women with primary dysmenorrhea were randomly assigned to one of five four-times-daily treatment groups for a minimum of three days and a maximum of five days. Three of the groups received different initial single-daily doses of piroxicam, which were followed on each treatment day with placebo for the second through fourth doses, namely, piroxicam 20 mg daily for five days (piroxicam 20 mg for five days); piroxicam 40 mg on Day 1, followed by piroxicam 20 mg on Days 2 through 5 (piroxicam 40 mg for one day); and piroxicam 40 mg on Days 1 and 2, followed by piroxicam 20 mg on Days 3 through 5 (piroxicam 40 mg for two days). The fourth group received ibuprofen 400 mg four times per day, and the fifth group received placebo four times per day. Patients determined the severity of overall discomfort and pelvic-abdominal pain at baseline and prior to each dose using a four-point numerical scale. Supplemental ibuprofen, 400 mg four times per day, was provided for those patients requiring additional pain relief. Patients also made a global determination of overall relief at the end of the study. At 24 hours, the results revealed that piroxicam 40 mg for two days, piroxicam 20 mg for five days, and ibuprofen provided significantly more relief of overall discomfort compared with placebo (p = 0.003, p = 0.018, and p = 0.026, respectively). All four active treatment groups also experienced significantly more relief of pelvic-abdominal pain compared with placebo: piroxicam 40 mg for two days followed by three days of 20 mg (p = 0.002), piroxicam 40 mg for one day followed by four days of 20 mg (p = 0.023), piroxicam 20 mg for five days (p = 0.012), and ibuprofen (p = 0.011). A significantly smaller percentage of patients treated with piroxicam 40 mg for two days required supplemental medication as compared with those treated with piroxicam 20 mg for five days (p = 0.035) and patients treated with placebo (p = 0.010). A greater amount of overall relief was obtained by patients treated with piroxicam 40 mg for two days compared with patients treated with piroxicam 40 mg for one day (p = 0.041) and placebo-treated patients (p = 0.001). It was concluded that single daily doses of piroxicam 20 mg and 40 mg were as effective as ibuprofen, 400 mg four times per day, for the relief of primary dysmenorrhea.