The clinical profile and outcome of nosocomial and non-nosocomial health care-associated native valve endocarditis are not well defined.To compare the characteristics and outcomes of community-associated and nosocomial and non-nosocomial health care-associated native valve endocarditis.Prospective cohort study.61 hospitals in 28 countries.Patients with definite native valve endocarditis and no history of injection drug use who were enrolled in the ICE-PCS (International Collaboration on Endocarditis Prospective Cohort Study) from June 2000 to August 2005.Clinical and echocardiographic findings, microbiology, complications, and mortality.Health care-associated native valve endocarditis was present in 557 (34\%) of 1622 patients (303 with nosocomial infection [54\%] and 254 with non-nosocomial infection [46\%]). Staphylococcus aureus was the most common cause of health care-associated infection (nosocomial, 47\%; non-nosocomial, 42\%; P = 0.30); a high proportion of patients had methicillin-resistant S. aureus (nosocomial, 57\%; non-nosocomial, 41\%; P = 0.014). Fewer patients with health care-associated native valve endocarditis had cardiac surgery (41\% vs. 51\% of community-associated cases; P