The composition and concentration of monoterpenoids in the leaves and stems of Artemisia feddei and Artemisia scoparia were determined, and seasonal variation in the monoterpenoids of Artemisia species were investigated. The two species possessed different compositions and concentrations of monoterpenoids. The total amount of monoterpenoid in A. scoparia was always higher than that of A. feddei, and the monoterpenoid yields of leaves were higher than stem yields in both species as compounds formed. The major constituents of A. scoparia were 25 while A. feddei consisted of 26 compounds. Sixteen common monoterpenoid compounds were found in both plants. Large differences in the relative amounts of the monoterpenoids were found between species and seasons. Extremely large differeces in the relative amounts of naphtalene, sabinene, $eta$-pinene, cyclohexene, and octatrine were found in the leaf monoterpenoids of the two species. The largest differences in relative amounts of stem monoterpenoids were in a abinene and $eta$-pinene levels.