Bacterial endocarditis is a serious condition with high lethality. The authors review the etiology of the disease and conditions and procedures associated with increased risk, and give recommendations on choice and dosage of effective antibiotics. Most cases of endocarditis are caused by gram-positive cocci of the genera Streptococcus, Enterococcus or Staphylococcus. The number of cases caused by staphylococci has increased in recent decades. Risk of acquiring endocarditis is higher, for example, in patients with prosthetic cardiac valves and in patients with a previous history of endocarditis. Interventions associated with increased risk include various procedures in the mouth, throat and upper airways, since this is where the bacteria most often causing endocarditis are to be found. A single oral dose of amoxycillin is recommended for standard prophylaxis, and ampicillin in combination with an aminoglycoside for parenteral use. In cases of penicillin allergy, a single oral dose of clindamycin is recommended in patients at risk of bacteriemia from the respiratory tract, with trimetoprim as an alternative for genito-urinary and gastrointestinal procedures. Vancomycin or vancomycin plus aminoglycoside is recommended as a parenteral regimen in cases of penicillin allergy.