Erythroderma with complicated etiology is one of the severe skin diseases and has high mortality,of which the incidence was 0.5％-1.5％ in skin diseases.Erythrodermic psoriasis (EP) is the commonest type of erythroderma.In addition,there are drug-induced erythroderma,erythroderma secondary to preexisting dermatoses,malignancy-related erythroderma,and idiopathic erythroderma of unknown etiology.Erythroderma of different etiologies has various clinical manifestations,resulting in relevant curative effects and outcomes.In this article,we retrospectively investigated 205 erythroderma patients about clinical symptoms,auxiliary examination and treatments,and evaluated the efficacy and prognosis.There were 84 cases of EP among 205 patients,10 cases of erythroderma caused by specific drugs,77 cases of erythroderma secondary to preexisting dermatoses (excluding psoriasis),7 cases of erythroderma patients suffering from malignancy and 27 cases with unknown causes.We concluded that the etiology of male patients in different age groups had significant difference.The incidence of EP was the highest among all types.The EP was commonly accompanied with hypoproteinemia,and changed into psoriasis vulgaris after treatment.Drug-induced erythroderma was commonly accompanied with fever,and mostly cured by systematic steroid therapy.For erythroderma secondary to preexisting der matoses,the original dermatoses must be actively treated to achieve a satisfying prognosis.Erythroderma with malignancy or unknown causes had long-term duration,poor response to the treatment,and high potential to relapse.Therefore,clarifying the etiology,providing an appropiate and individual regimen,and regular follow-up are crucial for the successful treatment of erythroderma with unknown causes.