In a double-blind, placebo-controlled crossover trial, 23 patients consumed 250 ml mare's milk or placebo for 16 weeks. The aim was to examine the effects of mare's milk on the characteristics of atopic dermatitis (AD), on faecal microbiota and on clinical and immunological parameters. The intensity of AD was examined using the Severity Scoring of Atopic Dermatitis (SCORAD) index. During the mare's milk period, the mean SCORAD value of patients (n=23; 17 females, 6 males) decreased from 30.1 to 25.3 after 12 weeks (P<0.05) and to 26.7 after 16 weeks (P<0.1). In a subgroup (n=7) the SCORAD index and especially the pruritus decreased by 30% through the mare's milk period (P<0.01). In this subgroup, the faecal bifidobacteria increased during the mare's milk period from 4.6% to 11.9% of eubacteria (P<0.05). The immunological parameters, except C-reactive protein, were unchanged.