We report the case of a 52-year-old man with hyperazotemia of indeterminate source, who had a history of benign prostatic hypertrophy and chronic prostatitis, which was treated for several months with SAW PALMETTO, a medicine based on extracts from the American dwarf palm fruit. During the last week the patient had received high doses (960 mg/day). Laboratory workup revealed a glomerular filtration rate of 60 milliliters per minute; the suspension of this herbal remedy achieved restoration of renal function to normal levels. We discuss the mechanisms through which saw palmetto could cause hyperazotemia.