ABSTRACT To the Editor.— In a letter by Jansen (226:1361, 1973) commenting on the article titled, "Lipoid Pneumonia Caused by Methenamine Mandelate Suspension," by Timmerman and Schroer (225:1524, 1973), it was implied that methenamine mandelate tablets are available only as entericcoated tablets. At least one pharmaceutical firm (Reid-Provident Laboratories, Atlanta) markets this product as a tablet which is not entericcoated (Prov-U-Sep). There are a number of other tablet-dosage forms on the market containing methenamine or a form of methenamine as the only active ingredient or combined with other drugs, which are not enteric-coated. While the current edition of Drug Evaluations, Pharmacopeia of the United States (USP) does indicate that "methenamine mandelate tablets are enteric-coated," previous editions did not refer to the tablets in this way; and the 19th edition of USP, to become official at the end of this year, will have a permissive statement, "methenamine mandelate tablets may be enteric-coated".