Abstract: Childhood psoriasis is more extensive and severe compared with that of adults. Therefore an effective and safe treatment modality is needed. Although a few studies of childhood psoriasis indicate that treatment with calcipotriol is safe and effective, short-term studies cannot reflect the exact effect of calcipotriol on systemic calcium homeostasis. Our purpose was to study the long-term efficacy and safety of calcipotriol for childhood psoriasis. An uncontrolled pilot study, with long-term follow-up for as long as 106 weeks, using open-label calcipotriol ointment was conducted in 12 psoriasis patients less than 15 years of age. Response to treatment was assessed by the psoriasis area and severity index (PASI) and serum 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 levels, as well as routine laboratory analyses including serum calcium and phosphate, which were measured before and after the course of treatment. At the end of the study, the patients showed significant improvement in PASI scores compared with the baseline level. No serious side effects, including those related to calcium homeostasis, were detected. The mean values of 1,25-dihydroxyvitamin D3, however, were decreased and half of the patients had levels below the normal range. In conclusion, it is thought that calcipotriol ointment is an effective treatment modality for long-term use in childhood psoriasis. However, although not lowering serum calcium and phosphate levels, the long-term use of calcipotriol in childhood may possibly decrease the serum values of endogenous vitamin D. Therefore monitoring of vitamin D metabolites may be necessary during calcipotriol therapy. More investigative studies are needed to resolve this issue.