Maesil (Prunus mume Siebold & Zucc.), a potential source of free radical scavengers and inhibitor of pro-inflammatory mediators, is used in traditional Korean medical preparations as a remedy for skin disorders as have probiotics. The action of a probiotic fermented Maesil preparation on the development of atopic dermatitis (AD)-like skin lesions was determined in a NC/Nga mouse model as an initial step towards the development of a therapeutic feed supplement for use in dogs. Continuous ingestion of the experimental feed markedly inhibited the development of the AD-like skin lesions, as evidenced by a marked decrease in skin signs and reduced inflammation within the skin lesions. Efficacy was confirmed by significant decreases in eosinophil ratio and serum IgE concentration, and a reduction in the number of Staphylococcus aureus recovered from the ear. Relative mRNA expression levels of IL-4, interferon-gamma and tumour necrosis factor-alpha in the spleens of the experimental animals were also decreased and there was an increased serum concentration of IL-10 with a concurrent decreased IL-4 concentration in comparison to a control group. Taken together, the results indicate that some component(s) of fermented Maesil have the ability to suppress the development of AD-like skin lesions, possibly by stimulation of IL-10. Beneficial effects of fermented Maesil may thus be expected in dogs with AD, although this and the nature of the active pathway remain to be explored.