The English language literature that addresses the relationship between acetylation phenotype and clinical response to monoamine oxidase inhibitors is reviewed. In all, seven studies have been published in the last 20 years. Historical antecedents leading to interest in the relationship between acetylation phenotype and monoamine oxidase inhibitors are examined. Each study is then summarized, with comments about its relative merits and deficiencies. The review concludes that the data published do not support the notion of a correlation between acetylation phenotype and clinical response to monoamine oxidase inhibitors.