The Fontan operation palliates the effects of single ventricle congenital heart disease. To provide mechanical support for patients who have undergone this operation Penn State University is developing an implantable Fontan Circulation Assist Device (FCAD). This study quantified flow fields within the FCAD using particle image velocimetry (PIV). Flow fields were acquired at the centerline of the two inlets and the outlet of the model under various flow conditions.