Atopic dermatitis (AD) is a common multifactorial chronic skin disease that has a multiple and complex pathogenesis. AD is gradually increasing in prevalence globally. In NC/Nga mice, repetitive applications of 2, 4-dinitrofluorobenzene (DNFB) evoke AD-like clinical symptoms similar to human AD. Aspartame (N-L-α-aspartyl-L-phenylalanine 1-methyl ester) is a methyl ester of a dipeptide, which is used as an artificial non-nutritive sweetener. Aspartame has analgesic and anti-inflammatory functions that are similar to the function of nonsteroidal anti-inflammatory drugs such as aspirin. We investigated whether aspartame can relieve AD-like clinical symptoms induced by DNFB treatment in NC/Nga mice. Sucrose did not relieve AD-like symptoms, whereas aspartame at doses of 0.5 μg kg(-1) and 0.5 mg kg(-1) inhibited ear swelling and relieved AD-like clinical symptoms. Aspartame inhibited infiltration of inflammatory cells including eosinophils, mast cells, and CD4(+) T cells, and suppressed the expression of cytokines including IL-4 and IFN-γ, and total serum IgE levels. Aspartame may have therapeutic value in the treatment of AD.