A multi-clinical double-blind study on therapeutic effect of combination preparation of vitamins E and C was undertaken in comparison with single preparation of vitamin E and vitamin C in the treatment of chloasma or pigmented contact dermatitis (PCD). Combination treatment resulted in significantly better clinical improvement than vitamin C alone in both diseases. Objective data compiled from color difference measurements and color photographs revealed significantly better results with combination treatment in chloasma than vitamin C alone and, in PCD, than vitamin E or C alone. Differences in skin luminosity between hyperpigmented and normal areas significantly decreased in all three groups, with the combination group producing the most significant change. The total serum lipoperoxide level and its ratio to total serum lipids tended to decline in the combination group, and decreased significantly in vitamin E group. The sebum lipoperoxide level decreased significantly only in the combination group (EC).