The recent success of vitamin D and its analogues in the treatment of psoriasis has generated extensive research into the role of vitamin D and calcium in this hyperproliferative skin disease. This study aimed at studying the calcium serum level in patients suffering from psoriasis. In this case control studies, 98 hospitalized cases with psoriasis were compared with 100 patients who were hospitalized due to other diseases. Two groups were matched for age and gender. The type of psoriasis, age and sex of patients and serum calcium and albumin levels in two groups were documented in a especial questionnaire. Of all 98 patients with psoriasis, 37.2% were hypocalcemic and 63.7% had normal serum calcium. There was no hypercalcemia. In other group 9% were hypocalcemic, 89 and 2% were normocalcemic and hypercalcemic respectively. In 64.9% of hypocalcemic psoriatic patients, low serum albumin was noted. But all of control group had normal levels. Hypocalcemia is a risk factor of psoriasis. It is better to include dairy as calcium resource in daily diet of patients suffering from psoriasis.