Linear scleroderma is a connective tissue disorder that characteristically involves the skin. Skin induration and pigmentary changes present in a linear distribution. Severe functional and cosmetic disability may occur, especially in growing children. No effective therapy for the fibrotic stage of scleroderma is available at present. Recently a beneficial effect of oral 1, 25-dihydroxyvitamin D3 (calcitriol) treatment was reported in adults. Calcitriol has a dose-dependent inhibition on fibroblast proliferation and collagen synthesis and has immunoregulatory activities. We assessed the efficacy of oral calcitriol treatment in seven pediatric patients with linear scleroderma. During the treatment dietary calcium intake was restricted. Calcium, inorganic phosphate, creatinine, and urea in the serum and urine was monitored. The urinary calcium:creatinine ratio was measured. The effects of the treatment were evaluated using a clinical scoring system. No side effects were observed. Five of the seven patients showed a good to excellent improvement of their lesions. One of them partly relapsed after 19 months, but showed an excellent response to a second therapy session with calcitriol. One patient with rapidly progressive disease failed to respond to therapy. Our results indicate that calcitriol can be an effective agent for treating localized scleroderma in children.