Background: Erythroderma is a rare skin disorder and studies on its causes and prognosis are rare in the literature. Objectives: We reviewed the clinical, laboratory and biopsy materials of 260 patients diagnosed with erythroderma who were treated in our department over an 11-year period. Patients were followed up to better understand the evolution of erythroderma. Methods: This study was performed at our hospital between January 2001 and 2012 and included 260 patients with erythroderma. We recorded epidemio-clinical, biological and histological data, treatments and outcomes. Clinical-histological correlation was analyzed. Overall survival and relapse-free survival for a limited number of etiologies were described using Kaplan-Meier estimates. Results: The mean age at onset in this study was 52.57 ± 17.94 (SD) years (range 13–87), with a male-to-female ratio of 3:1. Acute onset was present in 15.38% of patients. Clinical findings were dominated by pruritus (87.69%), fever (40%), edema (37.69%), chills (31.15%), nail changes (29.62%), weakness (19.23%), lymphadenopathy (19.23%), weight loss (14.62%) and islands of normal skin (13.46%). Skin biopsies revealed the cause in 55.56% (65/117) of the patients. The most common causative factors were pre-existing dermatoses (70.77%), followed by idiopathic causes (14.23%), drug reactions (12.69%) and malignancies (2.31%). Among the pre-existing dermatoses, psoriasis was the most common etiology (143/260, 55%). In the drug-induced group, carbamazepine was the most frequently implicated drug in our study (33.33%). Chinese traditional herbal medicines are among the causes of drug-induced erythroderma as well. We also found that Langerhans cell histiocytosis, tongue cancer, hypereosinophilic syndrome, bullous pemphigoid and dermatomyositis could be causes of erythroderma. From our follow-up study, 39 (31.2%) of the 125 patients from whom information was available had relapsed. The patients with idiopathic erythroderma had a higher relapse rate. Of the 5 patients who died, 4 deaths were directly related to erythroderma. Conclusion: Most of the clinical features of erythroderma are unspecific with few cause-orienting clues. Although numerous laboratory values were abnormal, most findings were nondiagnostic and were related to the inflammatory process, except for skin biopsy. Our study had a high percentage of erythroderma secondary to pre-existing dermatoses and a low percentage of malignancy patients. Repeated evaluations, close follow-up and biopsy are recommended.