Wells' syndrome is an inflammatory dermatosis with associated aberrant eosinophil responses caused by unknown factors. Its histology is characterized by erythematous plaques with "flame figures" in the dermis, which is potentially diagnostic but not pathognomic. Cases of Wells' syndrome in patients with Churg-Strauss syndrome (CSS), which is characterized by antineutrophil cytoplasmic antibody-related necrotizing vasculitis, marked peripheral eosinophilia, and eosinophil tissue infiltrates, have rarely been reported, and the pathogenic association between these two diseases remains undetermined. Differences of clinical and histopathologic features of these two diseases suggest that they are distinct disease entities, even though, in part, they share pathogenic mechanisms. Here we present a new case with Wells' syndrome in a patient with CSS, treated with systemic steroid.