A stability-indicating assay for furosemide based on high-pressure liquid chromatography was developed. The method is sensitive, accurate, and precise. The standard deviation based on six injections of the standard solution was +/- 1.37%. This method was used to study furosemide stability in various aqueous solutions and dosage forms. Stability tests were conducted at room temperature as well as at higher temperatures (45, 65, and 85 degrees) at various pH values and with different vehicles. Some decomposition products were identified.