Abstract: Employing mouse vaginal epithelium and modle tail scale epidermis as experimental modals,the authors studied the pharmacologic activitire of N-methyIisoindigotin (meisoindigo) sad other 3 di-ixtdole compounds in relation to the treatment of psoriasis. The results supported the previous clinical observation on treating psoriasis with meisoindigo and provided the pharmacodynamic basis for the clinical use of the drug. The promotive effect om orthokeratinization of the 4 di-indole compounds studied was obsezved to be stronger than the inhibitory effect on mitmsis, suggesting that tine mode of action of these compounds be different from cytotaxica. All of the 4 compondsn significantly raised the plasma cANP/cGMP ratio in mice, suggesting a possible mechanism of the effect of these compounds in relatiou to the treatment of psoriasis.