Curcumin is a complementary therapy that may be helpful for the treatment of psoriasis due to its anti-inflammatory, antiangiogenic, antioxidant, and antiproliferative effects. In the present study we performed a randomized, double-blind, placebo-controlled clinical trial to assess the effectiveness of a bioavailable oral curcumin in the treatment of psoriasis. Sixty-three patients with mild-to-moderate psoriasis vulgaris (PASI < 10) were randomly divided into two groups treated with topical steroids and Meriva, a commercially available lecithin based delivery system of curcumin, at 2 g per day (arm 1), or with topical steroids alone (arm 2), both for 12 weeks. At the beginning (T0) and at the end of the therapy (T12), clinical assessment and immunoenzymatic analysis of the serum levels of IL-17 and IL-22 were performed. At T12, both groups achieved a significant reduction of PASI values that, however, was higher in patients treated with both topical steroids and oral curcumin than in patients treated only with topical steroids. Moreover, IL-22 serum levels were significantly reduced in patients treated with oral curcumin. In conclusion, curcumin was demonstrated to be effective as an adjuvant therapy for the treatment of psoriasis vulgaris and to significantly reduce serum levels of IL-22.