Objective To summarize the clinical dosage features of Cortex Fraxini from Western and Eastern Han Dynasties till now so that to provide evidence for making strategy in clinical dosage of Cortex Fraxini. Methods A database of Cortex Fraxini dosage in past dynasties was established. The most representative medical works in each dynasty were chosen. Information on prescriptions containing Cortex Fraxini

including the total medicine quantity

quantity of Cortex Fraxini

number of ingredients

water amount and administration instructions were recorded. The frequency of Cortex Fraxini occurrence

common dosage

upper dosage limit

lower dosage limit

maximum dosage

minimum dosage and average dosage were figured out. The features of clinical dosage of Cortex Fraxini in past dynasties were analyzed. Results In Han

Tang

Ming and Qing dynasties

dosage of Cortex Fraxini reached the top

with the daily amount around 40 g. While in other dynasties

it was rarely used or the amount was only around 10 g.Conclusion Large dose of Cortex Fraxini（ around 40 g） has the effect of clearing away heat and removing dampness in large intestines

so it can be used for severe dysentery due to heat-toxin. Medium dose of Cortex Fraxini（ around10 g） has the effect of inducing astringency and tonification

so it is used for eye diseases

leukorrheal diseases

uterine bleeding and essence deficiency of male.