The renal side effects of nonsteroidal anti-inflammatory drugs are very often and could be seen in 5% of patients who are treated with this drugs. These side effects could be separated in 5 clinical syndromes: 1. acute renal failure, 2. acute interstitial nephritis with nephrotic syndrome, 3. electrolyte and fluid disorders, 4. hypertension and 5. analgesic nephropathy. There are a lot data in the literature which suggest that selective COX-2 inhibitors (rofecoxib and celecoxib) produce the similar effects on the kidney as traditional nonsteroidal anti-inflammatory drugs (inhibitors of COX-1 and COX-2).