In mental clinics, bromide agents such as potassium bromide were often once used as therapeutic drugs to treat psychiatric disorders. They were also given as hypnotic, sedative and antiepileptic medicines. However, the appearance of new medicines has resulted in them not being used for these purposes in recent years. Potassium bromide is still continuously listed in today's JP and BP. This suggests that it maintains value as a basic medicine for treating mental disorders in the history of psychotropic medicines. However, regarding the standards and test methods for potassium bromide in the present JP, as a result of a comparison between the USP of the same age, BP and EP, a gap is seen, and this is very regrettable. The exchange of art and scientific information related to medical sciences with foreign countries is becoming more active today. Therefore, scholarly information overseas should be collected and reflected in the standards and test methods for potassium bromide adopted in the JP of Japan. The author believes that the standards and test methods comparable to those at the international level should introduced. On the other hand, potassium bromide was recetnly relisted by USP29 (2006) for the first time in approximately 50 years. Moreover, instrumental analysis was introduced as part of the test methods in BP2013; that is, an epoch-making revision was made in terms of test methods. It is assumed from this that there is a sign of new change regarding the existence of potassium bromide as hypnotic, sedative and antiepileptic medicines, and its utility value. It is believed that the sign of change in view of the utility value and pharmacological evaluation probably arose with the new clinical knowledge that potassium bromide was used to treat a baby seriously ill with myoclony epilepsy, as well as to treat a dog with epilepsy.