Abstract: Objective To explore the influence of rupatadine in treating patients with chronic idiopathic urticaria(CSU)and its effects on T cell subsets in peripheral blood. Methods A total of 80 patients with CSU were divided into two groups. The treatment group was given oral administration of rupatadine fumarate tablets, while the control group was given loratadine for oral administration, the course of treatment was 12 weeks. The disease conditions of patients in the two groups were evaluated before treatment and at 4, 8 and 12 weeks after treatment, and their adverse reactions and recurrence conditions were recorded. Besides, 35 healthy people with physical examinations were selected as healthy group. The peripheral venous blood before treatment and after 12 weeks of treatment was collected from all the included subjects, and levels of T lymphocyte subsets were detected. Clinical urticaria activity symptom score(UAS7)was compared between treatment group and control group after treatment. Results After 12 weeks of treatment, the total effective rate of the treatment group was 90.63%, which was significantly higher than 65.63% of the control group, and the recurrence - rate of the treatment group was 12.12%, which was significantly lower than 37.50% of the control group, and the differences were statistically significant(P<0.05). After 4, 8 and 12 weeks of treatment, UAS7 scores in treatment group and the control group decreased significantly, and showed significant differences when compared with treatment before(P<0.05). At week 8 and 12 of the treatment, UAS7 scores of the treatment group were lower than that of the control group, and the differences were statistically significant(P<0.05). Before treatment, the levels of CD3⁺ and CD8⁺ in the treatment group and the control group were significantly lower than those in the healthy group, and CD4⁺/CD8⁺ ratio was significantly higher than that in the healthy group(P<0.05). After treatment, CD3⁺ and CD8⁺ in the treatment group and the control group were significantly increased, and CD4⁺/CD8⁺ ratio was significantly decreased compared with before treatment(P<0.05), and the change in the treatment group was more significant(P<0.05). After treatment, the levels of CD3⁺, CD4⁺, CD8⁺ and CD4⁺/CD8⁺ ratio in the treatment group were showed no significant difference compared with those in the healthy group(P>0.05). The levels of CD3⁺ and CD8⁺ in the control group were significantly lower than those in the healthy group and the treatment group, and the CD4⁺/CD8⁺ ratio was significantly higher than that in the healthy group and the treatment group(P<0.05). Conclusion Rupatadine is effective in the treatment of chronic spontaneous urticaria, and it has lower recurrence rate and less adverse reactions. Besides, it can effectively correct the disorder of T lymphocyte subsets in patients with chronic spontaneous urticaria.