Polyarteritis nodosa (PAN) is a vasculitis characterized by inflammatory necrosis of medium-sized arteries. Juvenile PAN and Kawasaki disease (KD) both cause vasculitis of the medium-sized arteries, and share common features. They have overlapping clinical features. Treatment should be managed according to the severity of symptoms and persistence of clinical manifestations. Herein is described the case of a 14-year-old boy first diagnosed with KD, who then fulfilled the criteria for juvenile PAN due to the development of severe myalgia, persistent fever, polyneuropathy and coronary arterial dilatation. He also had acute toxoplasmosis at the onset of vasculitis symptoms. The final diagnosis was of juvenile PAN associated with toxoplasmosis infection. Toxoplasma infection can be considered as an etiological agent for PAN and other vasculitis syndromes. Awareness of toxoplasmosis-related PAN facilitates early diagnosis, and instigation of appropriate treatment.