The potential of the yeast component, mannanoligosaccharide (MOS) to ameliorate the effects of aflatoxicosis was examined in growing Japanese quail. The product was incorporated in the diet at 1 g/kg and was evaluated for its ability to reduce the deleterious effects of 2 mg total aflatoxin (AF; 82.30% AFB1, 2.06% AFB2, 7.68% AFG1 and 7.96% AFG2)/kg diet on Japanese quail chicks from 10 to 45 days of age. Forty 10-d old Japanese quail chicks were assigned in a 2×2 factorial arrangement of treatments to four groups (Control, AF, MOS, AF plus MOS), each consisting of 10 quails. The addition of AF alone significantly decreased feed consumption and body weight gain from the first week onwards. A significant adverse effect of AF on the feed conversion ratio was also observed from week 4 onwards. The addition of MOS to the AF-containing diet significantly reduced these adverse effects of AF on feed consumption, body weight gain and feed conversion ratio. The cumulative body weight gain was 22.0% lower in the quails consuming a diet containing AF without MOS as compared to the control group. However, it was only 2.3% lower that the control in the birds fed the diet containing the AF plus MOS.