The taste function and the zinc and copper levels in serum and urine were followed for up tp 16 weeks in ten patients who were started on penicillamine therapy for generalized scleroderma (9 patients) and rheumatoid arthritis (one patient). During therapy the serum zinc concentration remained unchanged, whereas the serum copper concentration increased significantly during the first 4--5 weeks and then tended to decrease. Urinary copper rose significantly and remained considerably above the upper normal limit throughout the study. Six of the patients complained after about 4--5 weeks of a decreased taste function, which was gradually restored whether the medication was stopped or continued. The alterations in the taste acuity for sweet, salt, sour, and bitter significantly paralleled the variations in urinary copper before as well as during therapy. Thus, the patients who showed the most pronounced loss of taste, had a lower urinary copper output than those whose taste acuity was less disturbed.