Objective: Atopic dermatitis has a close relationship with degranulation of mast cell and separation of histamine. As there was no experiment with herb, using Lithospermum erythrorhizon, We investigated experimental influence of Lithospermum erythrorhizon on degranulation of mast cell and separation of histamine in Sprague-Dawley rats. Methods: The SD rats were classified into three groups. One group was a normal one treated by normal saline before medical treatment. The other was a control group prescribed to Compound 48/80 before normal saline treatment. And the third was a expenimental group prescribed to compound 48/80 after medical treatment of Lithospermum erythrorhizon. Then, We investigated the experimental results by measuring the degree of degranulation and separation of histamine. Results: Lithospermum erythrorhizon did obviously inhibit the degree of degranulation of mast cell(p<0.05). Lithospermum erythrorhizon inhibited the separation of histamine in the plasma. Conclusion: Lithospermum erythrorhizon may be one of the effective therapeutic regimens on atopic dermatitis