Primary cardiac lymphoma is extremely rare and lymphoma arising in association with prosthetic valves has been described in only 3 case reports. We describe 3 patients with diffuse large B-cell lymphoma (DLBCL) involving prosthetic heart valves and a synthetic tube graft. All 3 specimens showed shallow layering of acellular fibrinous debris over the prosthetic or synthetic materials, with tumor lymphocytes present at the luminal surface. There were frequent mitoses and abundant karyorrhectic debris. All demonstrated a nongerminal center B-cell phenotype. All 3 cases were positive for Epstein-Barr virus, but there was no staining for human herpes virus 8. There was no other evidence of distant disease at the time of diagnosis and no recurrence or dissemination occurred after surgical removal of the prosthesis, though follow-up was limited. On the basis of 2008 World Health Organization diagnostic criteria, we believe these cases should be classified as DLBCL associated with chronic inflammation. However, unlike the characteristically poor prognosis reported in this entity, we hypothesize that the disease resectability in these cardiac sites, in many cases, may allow for a better prognosis than DLBCL with chronic inflammation at other less resectable sites.