**1. Introduction**

Cardiac valve allografts have been utilized since the late 1960s predominantly for surgical treatment of single valve infective endocarditis, rheumatic heart disease, and congenital valve anomalies [1–4]. The absence of strict indication, challenging surgical technique, along with allograft shortage used to prevent them from being widely acceptable in everyday clinical practice. Due to recent scientific advances in cardiac valve anatomy and physiology, development in surgical and preservation techniques, cardiac valve allografts have demonstrated their feasibility in those clinical scenarios where common valve substitutes have not shown significant clinical superiority [5]. Moreover, in some rare clinical circumstances, the choice between different valve prostheses might be a rather tough decision-making process regarding immediate and long-term results. In our study, we tried to summarize our experience with cardiac valve allografts in unusual clinical situations. The pulmonary artery trunk allograft in the surgical treatment of inferior vena cava tumor involvement, monoblock aortamitral homograft for destructive double valve endocarditis, mitral valve allograft

in Bekhterev's disease, and mitral allograft (MA) for tricuspid replacement in a patient with large ostium secundum are consequently presented in our study. All four patients successfully underwent surgical repair in two departments with an uneventful postoperative course.
