A series of experiments was conducted to determine the feasibility of using mice to screen for possible dietary mycotoxin interactions before testing them with swine. Selected mycotoxins, deoxynivalenol (DON) and T‐2 toxin, were fed to young mice, alone and in combination. The severity of effects on body weights caused by DON (0–20 mg OONIkg diet) was more pronounced in a doss‐related manner when the animals were exposed to contaminated diets starting at 21 d of age than at 28 d (Experiment 1) as reflected in the analysis of variance. The relative variance among diets after 7 d was twice as great for the younger than for the older mice. In both age groups, the weight gain response was linear, similar to that seen in growing swine. In Experiment 2, a significant (p < .05) diet type × DON interaction for food consumption evident after 7 d, indicated that the effect of DON depended on the type of diet (freeze‐dried vs. regular mash). There was no difference in food efficiency between diet type, but a strong dose‐dependent effect due to DON was observed. When DON and T‐2 toxin were fed together to young mice, a significant (p < .001) linear decrease in weight gain and food consumption was observed after 7 d on the contaminated diet as the toxin concentration increased.