Abstract： Objective::Adalimumab (ADA) is expensive and rarely used among patients. However, its cost for moderate to severe chronic plaque psoriasis can now be reimbursed since its addition to the National Reimbursement Drug List (NRDL) in January 2020. Therefore, we conducted this study to estimate the medical cost of ADA and its influencing factors in patients with psoriasis using ADA and thus gain a better understanding of the effect of the NRDL adjustment in China.Methods::This retrospective study evaluated the medical cost of ADA before and after the addition of ADA to the NRDL (2018—2022) among 320 patients in a large professional dermatology specialty hospital. Descriptive analysis, Welch’s analysis of variance, and multiple regression analysis were used to evaluate the medical cost and influencing factors.Results::Before ADA was added to the NRDL, patients’ mean total cost and ADA cost were ￥24,243.56 ± 16,346.53 and ￥20,391.11 ± 14,440.69, respectively. After ADA became covered by the NRDL, the above 2 expenses decreased to ￥10,461.19 ± 7,554.66 and ￥8,775.27 ± 7,092.16, respectively. This significant decrease in the cost of ADA resulted in a significant 110.5-times increase in ADA use. Statistically significant differences were found in the total cost, patient type (outpatient/inpatient), insurance status (yes/no), reimbursement status (before/after), and age. Medical insurance reimbursement ( P < 0.001, β = -0.468, before reimbursement = 1, after reimbursement = 2) was the most significant influencing factor, followed by patient type ( P = 0.018, β = -0.215, outpatient = 1, inpatient = 2) and age ( P = 0.0046, β = -0.174). Conclusion::Medical insurance reimbursement is the most important factor affecting patients’ total cost of ADA by reducing the economic burden, enhancing the availability of ADA, and stimulating the need for treatment.