Clinical and laboratory tests were used to evaluate fourteen patients with senile erythroderma following eczema, and the results were compared with those from four patients with psoriatic erythroderma, two with Sézary syndrome, and twelve with prurigo chronica multiformis or nummular dermatitis. Characteristic laboratory findings included elevated serum squamous cell carcinoma-related antigens (SCC-RAg), high lactate dehydrogenase (LDH), peripheral-blood eosinophilia, and a decreased peripheral blood lymphocyte percentage. Following treatment, titers of SCC-RAg and LDH resumed normal levels with remission. In patients with senile erythroderma following eczema, serum IgE was quite high and varied but, in a few instances, was within the normal range. SCC-RAg and LDH may thus be considered useful as markers for evaluating disease conditions of the skin of patients with senile erythroderma following eczema.