Bacterial inflammation associated with artificial cardiac valves is a rare complication after valve replacement but is burdened with a high lethality. Whereas in the case of mechanical valves the infection involves the body's own tissues, bacterial colonisation of valves made of prepared biological material can also occur. The morphology of the bacterial inflammation was examined in a case of early postoperative endocarditis. Although the bacterial infection in the paravalvular tissues resulted in a purulent inflammation, the Ionescu-Shiley-bovine bioprosthesis remained free of inflammatory cells despite extensive vegetative bacterial growth.