Erythema nodosum belongs to a group of relatively common hypodermal inflammations. It occurs mainly among women, particularly young women. The etiology of the disease is not clear. Most frequently, changes appear on the surface of the frontal part of the shins. Initially, red nodules change in color to dark brown and then to yellow and green. There is neither dissolution nor cicatrization of the exanthema. Regression is frequent. We present a case of erythema nodosum caused by Ascaris lumbricoides infection as well as by an early Chlamydophila pneumoniae infection, whose etiology has rarely been described in the literature. We were not able to confirm which factor was responsible for the occurrence of the skin changes as treatment of both infections was effective and all skin changes later disappeared completely. Particular attention should be paid to the fact that precise diagnosis of a patient and the search for etiologic factors, even rare ones, are crucial to obtain good results with treatment of erythema nodosum.