Deep vein thrombosis (DVT) after femoral arterial access is a rare complication of left heart catheterization (LHC). The reasons for paradoxical venous clot formation after arterial access are identifiable in some cases but less clear in others. Here, we present one case of provoked DVT after femoral access followed by a second case in which clot formation appears to be spontaneous. Additionally, though each of the patients presented here demonstrated thrombus resolution, only one received anticoagulation. These cases highlight the complex pathophysiology of DVT following femoral arterial access and the challenges of management strategy selection.