Lithium, a simple monovalent cation, is the mainstay in the treatment of manic-depressive illness, but despite extensive research, its mechanism of action remains to be elucidated. Because lithium requires chronic administration for therapeutic efficacy and because its beneficial effects last well beyond its discontinuation, it has been postulated that lithium may exert major effects at the genomic level. We have previously shown that Yungmijihwangwon (YM) increase TH protein expression through antioxidant activity and unknown effects in vivo. In the pressent study, we have sought to determine if lithium in herbal medicine also increases the expression of endogenous gene known to be regulated by AP-1 and have therefore investigated the effects of herbal medicine on tyrosine hydroxylase (TH) levels. Male mice were treated with LiCl and herbal medicine for 30 days, and TH levels and dopamine level were measured in striatum using immunoblotting and ECD-HPLC. Herbal medicine treatment resulted in statistically nonsignificant increase in TH levels in mouse striatum. The precise therapeutic relevance of these effects is presently unknown.