Two hundred and twenty-eight episodes of infective endocarditis in adult patients (mean age 36 years) were reviewed retrospectively. There were 183 episodes (80%) of native valve, 15 (7%) early prosthetic valve and 30 (13%) late prosthetic valve endocarditis. The most common predisposing factor was rheumatic valvular disease (65%). None of the patients were intravenous drug users. According to the Duke criteria, the number of definite, probable and rejected episodes were 121 (53%,), 94 (41%) and 13 (6%), respectively. Additional minor criteria increased the number of definite endocarditis to 82%. The Duke criteria are not primarily intended to influence treatment decisions but are helpful in standardising research activities. The choice of the level of sensitivity or specificity of the criteria may be adjusted according to the aim of the study and prevalence of disease in a particular area. More sensitive criteria may be valuable in those countries where the prevalence of rheumatic valvular disease is still high. (C) 2001 Elsevier Science B.V. and International Society of Chemotherapy. All rights reserved.