The clinical manifestation of infective endocarditis is usually non-specific. The signs and symptoms may be due to various infections, auto-aggressive or rheumatologic diseases. In some cases symptoms of endocarditis can mimic neoplastic disease. It is essential to diagnose infective endocarditis correctly and start the treatment as soon as possible because the outcome of the disease may be severe or even fatal. The disease is caused by the vegetations, characteristic changes. Vegetation is a mass of different cells: platelets, inflammatory cells as well as fibrin and microorganisms. Lesions are usually found on the valves of the left heart and lead to local destruction of the inner layer of the heart muscle. Parts of vegetation may drift with the blood flow and become the cause of cerebral or peripheral thrombus. However neurological disorders such as temporary ischemic attack or stroke can by the first symptom of endocarditis, usually the disease starts with fever. Physician can also find a new murmur of valve regurgitation. It is important to emphasize that there is an growing number of endocarditis due to cardiosurgical and cardiological procedures, especially concerning prosthetic valve or permanent electrode implantation. Intravenous drug abuse by addicts also may lead to endocarditis, in those cases lesions are often found on the tricuspid and pulmonary valves. Generally the most common cause of infective endocarditis is Staphylococcus spp. Diagnosis of endocarditis is based on clinical investigation, echocardiography and blood cultures. Primary treatment consists of multidrug antibiotic therapy and has to be started as soon as possible. In some cases surgical intervention is necessary. As far as endocarditis is concerned it is also essential to know when patients should be given antibiotics as prevention treatment. The rules of prevention of endocarditis have changed many times for the last few years. In summary: although endocarditis is rare disease, it is often difficult to diagnose and may lead to death. Therefore it is important for physicians to have at least a basic knowledge of infective endocarditis.