Objective To observe the clinical effect and safety of Hongshen Wuzi Wan（ 红参五子丸） in treating primary hypothyroidism with spleen and kidney Yang deficiency. Methods Totally 80 patients with primary hypothyroidism with spleen and kidney Yang deficiency were randomly divided into a treatment group and a control group each group with 40 cases. Treatment group was given 10 g of Hongshen Wuzi Wan orally

three times a day

and 50μg of placebo of levothyroxine sodium tablets once a day. Control group was given equivalent levothyroxine sodium tablets and placebo of Hongshen Wuzi Wan. The treatments lasted for 3 months for both groups. Chinese medicine symptom scores were observed

levels of free triiodothyronine（ FT3）

free thyroxin（ FT4） and thyroid stimulating hormone（ TSH） were detected

and the improvement of disease

Chinese medicine syndromes and safety were compared before and after treatment. Results The total improvement rate of disease was 89. 74% in treatment group

and 86. 84%in control group

with no significant difference between the groups（ P > 0. 05）. The total improvement rate of Chinese medicine syndrome in treatment group was 97. 44%

which was much higher than 81. 58% in control group（ P <0. 01）. The scores of single symptom and total Chinese medicine scores in both groups were decreased after treatment

especially in the treatment group（ P < 0. 05）. Levels of FT3 and FT4 were increased and those of TSH were decreased in both groups

with no significant difference between the groups（ P > 0. 05）. Conclusion Hongshen Wuzi Wan is effective and safe in treating primary hypothyroidism with spleen and kidney Yang deficiency

and is superior to levothyroxine sodium tablets in improving symptoms of the disease.