Objective : This case report aims to demonstrate the effect of Oryeong-san on Insomnia.

Methods : A 26 year old woman suffered from insomnia with mental and physical exhaustion, reduced stamina, lack of concentration in daytime. According to Diagnostic system based on Shanghanlun provisions, the patient was diagnosed with Taeyang-byung and treated by Oryeong-san decoction. The result of administration was evaluated by Insomnia Severity Index.

Results : After administration of Oryeong-san decoction for 1 month, Insomnia Severity Index was decreased from 24(clinical insomnia, severe) to 1(no clinically significant insomnia).

Conclusions : The patient completely recovered from insomnia and daytime symptoms as treated by Oryeong-san decoction according to Diagnostic system based on Shanghanlun provisions.

KeyWords : Primary insomnia, Oryeong-san(五苓散), Diagnostic system based on Shang- hanlun provisions, Taeyang-byung(大陽病)