To observe the therapeutic effect of Kouchuangping granule (KCP,) on recurrent aphthae and explore its mechanism. Methods: One hundred and forty five patients treated with KCP were observed and compared with 49 patients treated with tripterygii multiglycoside tablet as control in controlling relapse, prolonging intermittent period, improving local symptom and the influence on humoral and cellular immunity. In animal experiment, the effects of KCP on immunologic function, anti exudation, anti inflammation and analgesia were studied. Results: The clinical markedly effective and cure rate of the KCP group was 62.8 and the total effective rate was 89.9%, which were significantly higher than those of the control group (40.8% and 75.5%, P<0.01, P<0.05). In the KCP group, the intermittent period of aphthous ulcer recurrence was prolonged to 6 months and the local symptoms were markedly improved, the differences were significant as compared with those before treatment and those in the control group (P<0.01 or 0.05 ). The KCP showed effects in suppressing humoral immunity and enhancing cellular immunity. Results of experimental study showed that KCP could inhibit the supernormal reaction of cellular immunity to prevent and treat the hypersentivity caused erosion and ulceration of mucous membrane, inhibit capillary permeability and WBC migration and abate the 5 hydroxytryptamine (5 HT) and histamine induced local swelling and pain. Conclusion:KCP has a significant effect in treating recurrent aphthae, the mechamism might be related with its effect on immunoregulation, anti inflammation and anti exudation. To observe the therapeutic effect of Kouchuangping granule (KCP,) on recurrent aphthae and explore its mechanism. Methods: One hundred and forty five patients treated with KCP were observed and compared with 49 patients treated with tripterygii multiglycoside tablet as control in controlling relapse, prolonging单词:periodic period, improving local symptom and the influence on humoral and cellular immunity. In animal experiment, the effects of KCP on immunologic function, anti exudation, anti inflammation and analgesia were studied. Results: The clinical markedly effective and cure rate of the KCP group Was 62.8 and the total effective rate was 89.9%, which were significantly higher than those of the control group (40.8% and 75.5%, P<0.01, P<0.05). In the KCP group, the intermittent period of aphthous ulcer recurrence was Prolonged to 6 months and the local symptoms were markedly improved, the differences were significant as compared with those before treatment and those in the The control group (P<0.01 or 0.05). The KCP showing effects in suppressing humoral immunity and enhancing cellular immunity. Experimental of experimental study showing that KCP could inhibit the supernormal reaction of cellular immunity to prevent and treat the hypersentivity caused erosion and ulceration of mucous单词: membrane, inhibit capillary permeability and WBC migration and abate the 5 hydroxytryptamine (5 HT) and histamine induced local swelling and pain. Conclusion: KCP has a significant effect in treating recurrent aphthae, the mechamism might be related with its effect on immunoregulation, anti inflammation And anti exudation.