Objective: The aim of this article was to discuss the composition rules of Tibetan medicinal formulas used to treat heat illnesses of the liver. Method: Formulas described for treating heat illnesses of the liver (mchin tshad) were selected from the rGyud bZhi. Frequency and association rules were analyzed by the statistical computing CRAN R software. Result: In this study

67 Tibetan medicinal formulas including 95 ingredients were found for treating liver heat illnesses. Among these formulas

the top 10 ingredients frequently used are:StigmaCroci

Calciosinti

Herba Swertiae Chirayitae

Bovis Calculus

Chebulae Fructus

Brag Zhun

Adhatoda Vasica

Herba Lagotis

Santali Albi Lignum and Caryophylli Flos. These 10 ingredients comprised 46.26% of the extracted formulas.A total of 204 association rules were found with a support value higher than 1 and a confidence higher than 0.7.Totally

6 most frequently cited association groups were derived

as the following:Chebulae Fructus-Fructus Termlnallae Billericae-Fructus Phyllanthi;Calciosinti-Bovis Calculus-Stigma Croci-Herba Lagotis-Herba Swertiae Chirayitae-Herba Aconiti Tangutici;Adhatoda Vasica-Calciosinti-Stigma Croci-Herba Swertiae Chirayitae-Bovis Calculu;Calciosinti-Stigma Croci-Santali Albi Lignum-Herba Lagotis;Fel Ursi-Stigma Croci-Brag Zhun; Bovis Calculus-Stigma Croci-Santali Albi Lignum-Calciosinti. Conclusion: The most common characteristic of the ingredients among the formulas derived is their cooling activity

as they are the common compounds used to treat general heat illnesses.Stigma Croci

the most frequently used compound has the effect of removing pathogenic heat and protecting the liver.Stigma Croci is also commonly used to enhance the efficacy of other formulas for treating the liver. The most commonly occurring compound groups derived by the current study all contain compounds which can protect liver and treat heat illnesses generally. Their taste composition is primarily sweet and bitter

which are the tastes described to treat heat illnesses in general.The target activity of such groups is described to increase the cooling and dulling quality within the bodily constituents such that the hot and sharp qualities of mkhris pa of heat illnesses are pacified.This study demonstrated that the composition rules of Tibetan medicinal formulas in the rGyud bZhi indicated for treating heat illnesses of the liver is consistent with the Tibetan medicinal compounding theory.As such

the compounding rules of Tibetan medicinal formula should be applicable to direct clinical practice.