The standard therapy for preventing copper accumulation in Wilson's disease, D-penicillamine, has been a life-saving drug, but it has many side effects and some patients are completely intolerant. We have been using oral zinc as another approach to the therapy for Wilson's disease, with copper balance studies as the key initial assessment of the adequacy of a given dose or regimen of zinc therapy. We earlier reported that an intensive regimen of zinc (zinc taken every 4 hr) was effective in controlling copper balance. We have now shown with balance studies that a simplified zinc therapy regimen of 50 mg zinc taken 3 times per day is effective in controlling copper balance. Preliminary work presented here with other simplified regimens also indicate their effectiveness. These studies increase the data base, in terms of copper balance, for zinc therapy of Wilson's disease, and expand the dose range and regimens of zinc which have been shown to control copper balance.