Abstract: Objective: To study the causes of erythroderma,the prognosis of patients and the influenceing factors. Methods: Clinical data from 52cases of erythroderma were retrospectively analyzed. Results: The mean age of onset was 41.7years old. The male-female ratio was 2.7:1.The most frequent cause of erythroderma was the exacerbation of a preexisting dermatosis (61.5%),among them patients with psoriasis accounted for 57.7%;followed by drug reactions(23.1%);malignancies and unknown-origin accounted for 3.8% and 11.5%,respectively.The inappropriate treatments (43.4%)were the main factor in inducing and aggravating erythroderma.In three of the patients who died,one cases was related to erythroderma,one died of malignancies.One died of heart failure.Conlusion:Erythroderma is mostly related to psoriasis,some are related to drug reactions and malignancies.erythroderma of unknown origin is related to insidious diseases.The prognosis of the disease depends on the causes and complications and therapeutics.Erythroderma caused by psoriasis is prone to recur while the prognosis of drug reaction related erythroderma is excellent.the prognosis of malignancies related erythroderma is worse.