The purpose of this study was to evaluate the prevalence of life-threatening renal failure (RF) caused by vasomotor nephropathy associated with nonsteroidal anti-inflammatory drug (NSAID) treatment (NSAID-RF) and risk factors for this renal impairment in an inception cohort of patients with recently diagnosed uremia treated by emergency hemodialysis in a prospective regional study. There are few published data on this phenomenon. Two hundred fifty-six patients (137 men, 119 women, mean age 68 years [22-95 years]) with acute uremia were treated with emergency hemodialysis in the intensive care unit over a period of 70 months. The patients were from an area of 231,000 inhabitants. Of the 256 patients, clinical data from a group of 79 patients with medical-type renal failure were analyzed in detail. The prevalence of NSAID-RF was 8%. This prevalence decreased to 4% when patients without any other medication affecting compensatory renal hemodynamics were considered. Moreover when nonpharmacological insults were not taken into account the prevalence decreased to only 1.6%. In 80% of the patients with NSAID-RF, nonpharmacological insults contributed to renal impairment. Both hypotension of cardiac etiology and dehydration/hypovolemia were present in 25% of the patients with this type of RF while urinary tract obstruction was seen in 1%. In 75% patients with NSAID-RF the underlying nephropathies were identified. NSAID-RF was not frequent. The population at greatest risk for renal functional alteration associated with NSAID therapy included patients with dehydration/hypovolemia, hypotension of cardiac etiology and those with pre-existing renal impairment, especially with vascular and analgesic nephropathy.