Abstract: This study explored the influence of isoflavone in red clover (Trifolium pratense cv. Minshan) on animal growth, organism immunity and antioxidant functions. Eighty female Sprague-Dawley rats (Rattus norvegicus) at the 50-60 day old were randomly and evenly assigned to eight groups. The rats in groups 1 to 7 with the ovary excised were given red clover isoflavone daily at the rates of 320, 160, 80, 40, 20, 10 or 0 mg/(kg·d) by gavage. The rats in group 8 were given the normal saline as the sham operation group. 1) Red clover isoflavone inhibited the growth of the ovariectomized rats to some extent, but there was no dose-dependent effect. 2) The transformation rate of T lymphocytes increased in response to the isoflavone at the lower doses, indicating that red clover isoflavone at the lower doses could be used as the immunopotentiator to improve the immunity of animals. The appropriate amount to add was 10 mg/(kg·d). 3) Red clover isoflavone had an obvious antioxidative effect. The correct addition (>80 mg/kg·d) may reduce the concentrations of CHO, HDL and LDL, but increase SOD activity in the serum. In addition, the isoflavone had a weak estrogen-like effect. The appropriate level for addition of the isoflavone was 80 mg/(kg·d) for the ovariectomized rats.