We present a case of histiocytoid cardiomyopathy resulting in sudden and unexpected death in a 4-month-old infant with Peter's Anomaly and congenital glaucoma. At autopsy, the granular histiocytoid cells that define this entity were found predominantly involving the conduction system, with encasement and partial replacement the His' Bundle. Large aggregates of these cells formed atrioventricular and nodoventricular connections, indicating a possible mechanism for the arrhythmias characteristic of the condition. The striking propensity for involvement of the conduction system in this case lends further support to the view that this disorder represents a developmental anomaly of the Purkinje cell system of the heart.