Three patients developed unilateral proptosis 13, 16, and 20 years after repair of blow-out fracture with orbital floor Teflon® implants. In one patient trauma preceded the onset of proptosis. In all three cases, the cause of the proptosis was probably hemorrhage of the capillaries in a fibrous capsule that surrounded the implant and that was evident on orbital CT scan. In two cases on CT scan, a retrobulbar cyst-like structure surrounded the implant, which was confirmed on ultrasonography. In the third case, an irregular soft-tissue density surrounded the implant. Histologically, a fibrous capsule surrounded the implant in all three cases, and in one case, the inner lining of the fibrous capsule was respiratory epithelium. The contents of the cyst-like structure, in two cases, were fresh blood and disintegrating red blood cells and blood products. In the third case, no cyst-like structure or “cyst” contents were identified; however, fibrous tissue containing hemosiderin-laden macrophages suggested the presence of an organized hemorrhage. The patients' proptosis resolved almost completely after surgical removal of the implant, decompression of the “cyst”, and partial removal of the “cyst” wall in two cases. The same result followed removal of the implant and part of the fibrous capsule in the third case.