Background: Although it has been reported that papuloerythroderma of Ofuji (PEO) often occurs in association with internal malignancy, the true incidence of malignancy in patients with PEO is unknown. Objective and Methods: To ascertain the incidence of and relationship with internal malignancy in patients with PEO, 11 patients with PEO diagnosed at our dermatology clinic between September 2005 and June 2011 were retrospectively reviewed. Results: Internal malignancy was found in 6 (54.5%) of the 11 PEO patients, and 5 cases were idiopathic PEO. In the 6 cases with associated malignancy, PEO preceded the malignancies, and the diagnosis of malignancy was made just before or shortly after the diagnosis of PEO, but the malignant process and PEO did not always run a parallel course. Conclusions: Although the limitations of this study included a relatively small sample size, the present findings show a high incidence of internal malignancy in patients with PEO.