The objective of this study was to evaluate the effect of fennel and thyme dietary supplements on the feeding of rabbits. Eighty-five weaned rabbits (35 days old), white New Zealand (of both sexes), were divided into four groups and submitted to the following dietary treatments: Control diet, diet F (Control diet + 2.5% Foeniculum vulgare seeds), diet T (Control diet + 2.5% Thymus capitatus leaves) and diet FT (Control diet + 2.5% Foeniculum vulgare seeds and Thymus capitatus leaves) for twenty-five days. The treatment with fennel and thyme had a beneficial effect on the mortality rate (18%). However the growth rate, feed conversion ratio and carcass yield were not influenced by dietary fennel and/or thyme supplementation. The antimicrobial effect of thyme (2.5%) was observed only against C. perfringens in the caecum (P < 0.05), but no effect was observed on the caecal count of or C. perfringens in the other treated groups.