Clinical and experimental studies have shown that renal and cardiovascular effects of most selective COX-2 inhibitors (rofecoxib, celecoxib) are similar to other traditional NSAIDs (dual COX inhibitors). In these study the effect of nimesulide--preferential COX-2 inhibitor, administration on 24-hour blood pressure profile was investigated in 40 adult individuals on antihypertensive therapy with pain states caused by osteoartritis. Nimesulide was administered orally, twice a day at the conventional dose of 0.1 g for five days. In the next (or previous) 5 days the same patients were administered with ketoprofen at the dose of 0.05 g three times a day. On the last day of the NSAID administration period, 24-hour blood pressure monitoring was performed. Our results indicate no difference between nimesulide and ketoprofen effects on mean blood pressure values during antihypertensive therapy.