In the sixty-five years since periarteritis nodosa was presented as a disease entity by Kussmaul and Maier, the accrued pathologic and clinical material has helped to clarify the conception of its symptomatology and pathogenesis. First considered solely as a medical curiosity, periarteritis nodosa now is known to be of significance in relation to certain other syndromes which, though more familiar, are none the less still obscure. In the classic case of Kussmaul and Maier1 the condition was at first considered clinically to be trichiniasis. These observers, therefore, regarded the diagnosis of periarteritis nodosa as possible if symptoms suggesting trichiniasis occurred in association with nephritis and enteritis and if biopsy of a muscle nodule showed pericapillary cellular infiltration but no trichinas. Since then, however, every discussion has emphasized the protean manifestations and the rarity of a correct diagnosis during life. P. S. Meyer (1878) suggested as the diagnostic formula of