Objective: To investigate the therapeutic efficacy of Gandou Tablet Ⅰ (肝豆片Ⅰ号) in tre ating hepatolenticular degeneration (HLD) and its effect on urinary trace element in 24 hours. Methods: Thirty-four patients with HLD took Gandou Tablet Ⅰ for 4 weeks, their changes of symptoms, signs and d aily life patt were observed closely, and the levels of urinary trace element in 24 hours before the therapy an d every week after initiation of treatment were measured. Result s: The total effective rate reac hed 70.59%, with markedly effective rate being 8.82%.The therapeutic effect was much better in the child and mild patients. After treatment, the daily urina ry coppe r output was obviously increased every week compared with that before (P< 0. 01 ). Although i t was highly negative linear correlated with the duration of treatment (γ=-0.96 , P < 0.05 ), it has insignificant difference between any two weekly excretion of urin ary copper per 24 hours after treatment (P>0.05). So its effect on urinary copp er excretion was not decreased. Conclusion: Gandou Tablet Ⅰ could increase the output of urinary copper, hence it was effective in treating HLD wi thout apparent toxic or side reaction.