ElM (Eighteen Incompatible Medicaments) is an important component in Oriental pharmacology and is directly related to clinical prescriptions. Medical practitioners argued that the definite cause and meaning of ElM was ambiguous and therefore debated the issue of clinical application of the ElM. This study conducted an in-depth literary research on the origin, meaning and contents of ElM with the purpose to contribute in its efforts to be used clinically. Even after thousands of years have past since establishment of Oriental medicine. ElM is still tabooed and was an obstacle that hindered ideologies. Modern herbal medicine texts claim that the use of ElM can reduce treatment effects and promote poisoning and side effects. However, since long ago, there has been medical practitioners who reject this as false. Recently, poisoning caused by ElM has been claimed to be from the toxicity of the drug itself, rather than the result of interaction between the drugs. and therefore they suggest that ElM is not a forbidden domain. In addition. ElM showed a difference in number depending on the era. However, this can be understood not as a definite number. but instead as a warning to be careful during combination of drugs for use as clinical medicine. Historically. there were very few cases in which ElM was used for clinical tests and thus, the clinical value is not yet clear. However. some medical practitioners clinically applied it and found clear results for it. while others applied ElM directly to their bodies. which showed signs for the usefulness and potential of ElM for us. A more concrete and in-depth study must be made on ELM.