Dysfunctional regulatory T lymphocytes are important for the pathogenesis of psoriasis and atherosclerosis. We analyzed the severity of atherosclerosis and the concentration of regulatory cytokines in patients with psoriasis who were administered methotrexate or adalimumab for 12 weeks. We included 34 patients with psoriasis (17 each, administered methotrexate or adalimumab) and eight healthy volunteers. BMI, psoriasis area and severity index (PASI), body surface area (BSA), and at least 75% and 90% improvements in PASI were observed. The 10-year risk of fatal cardiovascular disease was estimated using Systematic Coronary Risk Evaluation charts. The plasma interleukin (IL)-10, IL-35, and transforming growth factor β1 (TGF-β1) levels were determined using enzyme-linked immunosorbent assay before and after the 12-week treatment regimen. PASI (P = .0006) and BSA (P = .0001) were positively correlated with the BMI, IL-35 (−0.38), and IL-10 (0.48) levels. Baseline IL-35 concentrations were the highest in healthy volunteers; the IL-10 and TGF-β1 level were the highest in the methotrexate group. IL-10 concentration decreased in both treatment groups (P = .02 for the methotrexate and P = .09 for adalimumab group), and IL-35 decreased in the adalimumab group (P = .019), consistent with skin lesion recovery. Thus, this study demonstrates the dysregulated secretion of regulatory cytokines in psoriatic patients under systemic treatment.