OBJECTIVES: To assess the average prescribed daily dose and cost of the two reimbursed coxibs, rofecoxib and celecoxib, in Norway. Given the drugs' different price structures, prescribed number of tablets and strength impact the daily treatment cost differentially. As a prerequisite for continued general reimbursement for rofecoxib and celecoxib from July 1, 2003, the Norwegian Ministry of Health required post-marketing data regarding prescription patterns in clinical practice to further evaluate the drugs' relative cost effectiveness. The Ministry's re-evaluation will be based on this and other studies. METHODS: All accessible physicians within the field of rheumatology (specialists) in Norway were invited to prospectively register their prescriptions of reimbursed coxibs for patients with Rheumatoid Arthritis (RA) and/or Osteoarthritis (OA), over a period of 2 months (October to December 2002). Data from registration forms and patient records were collected through personal interviews with physicians. RESULTS: Prescriptions for 276 patients (66 % women), average age 56 years (18 - 88), were collected from 20 specialists. A total of 249 patients had RA (90%), 15 OA (5%) and 12 both (4%). Fifty-three percent were celecoxib prescriptions, 47 % rofecoxib. Eighty-four percent of 117 rofecoxib prescriptions to RA patients were of 25 mg strength. Of these, 95 % were dosed 1x1 and the average daily number of tablets was 1.05. Ninety-four percent of 132 celecoxib prescriptions to RA patients were of 200 mg strength. Of these, 68 % were dosed 1x2, and the average daily number of tablets was 1.86. The average weighted cost per day for celecoxib was NOK 16.75, and 11.78 for rofecoxib (pharmacy selling prices). CONCLUSION: This study by itself does not allow for an assessment of the drugs' relative cost-effectiveness. However, the prescription pattern observed among specialists for reimbursed cox-2 inhibitors for RA patients indicates a higher daily drug cost for celecoxib than for rofecoxib.