Abstract: A follow-up study of 213 outpatients with psoriasis beiag treated during the period of 1949-1976 was reported. It disclosed, apart from the common characteristics of the disease, that the severity of the disease was not related to the sex, age and mode of onset of the patient, the time when the patient came to the clinic to seek medical advice, and with or without family history of psoriasis and alcohol addict. But it was markedly relatod to the course of the disease and also the anticancer drugs used. Although anticancer drugs has a temporary effect against the disease, they may eventually worsen the patient's resistance. The use of these drugs should therefore be carefully restricted or even relinquished. Of the 213 cases, seven developed malignant tumours. The incidence is 8.4 times higher than that of the normal population of the same age group in the locality(p<0.001).Of the eleven patients who died five died of malignant tumour. It is therefore necessary to give more attention to the relationship between malignant tumour and psoriasis.