This study examined the vulnerability of the Michigan Alcoholism Screening Test (MAST), a widely used, direct alcohol inventory, to positive dissimulation. An earlier study by developers of the MAST suggested that most alcoholics were unable to alter their scores and thereby avoid detection by the instrument. But closer examination indicated that a standard scoring procedure was not employed. This study examined the ability of alcoholics to avoid detection by the MAST when using a standard scoring procedure. As predicted, alcoholics readily manipulated their MAST scores and avoided detection when so motivated. These results are discussed, indications and contraindications for use are included, and recommendations regarding future research are made.