Computer simulation using a two-phase model of the cell cycle has demonstrated that a transitory shift in the normal balance between the rate of cell flow to the differentiated and that to the proliferative compartment is sufficient to cause a permanent increase in the germinative population, thus resembling the alteration found in psoriasis. This shows the coherence of the hypothesis that cell kinetic parameters need not necessarily be expected to differ in psoriasis as compared with normal epidermis. This theoretical demonstration raises the possibility that the psoriagenic agent need not necessarily be present as long as the symptoms of psoriasis persist. From a therepeutic point of view this has implications that are sifficiently evident to warrant communication of this work.