Introduction: Data on infective endocarditis (IE) in Southeast Asia are scarce. Objectives: To describe the clinical epidemiology of IE in Lao PDR, a lower middle-income country. Methods: A single centre retrospective study at Mahosot Hospital, Vientiane. Patients aged over 1 year of age admitted 2006-2012 to Mahosot Hospital with definite or possible IE by modified Duke criteria were included. Results: Thirty-six patients fulfilled the inclusion criteria; 33 (91.7%) had left-sided IE. Eleven (30.6%) had definite IE and 25 (69.4%) possible left-sided IE. Median age was 25 years old [IQR 18-42]. Fifteen patients (41.7%) were males. Underlying heart diseases included: rheumatic valve disease in 12 (33.3%), congenital heart disease in 7 (19.4%), degenerative valve disease in 3 (8.3%), and of unknown origin in 14 (38.9%) patients. Native valve IE was present in 30 patients (83.3%), and prosthetic valve IE in 6 patients (16.7%). The most frequent pathogens were Streptococcus spp. in 7 (19.4%). Blood cultures were negative in 22 patients (61.1%). Complications included: heart failure in 11 (30.6%), severe valve regurgitation in 7 (19.4%); neurological event in 7 (19.4%); septic shock or severe sepsis in 5 (13.9%); and cardiogenic shock in 3 patients (8.3%). No patient underwent heart surgery. Fourteen (38.9%) had died by follow-up after a median of 2.1 years [IQR 1-3.2]; and 3 (8.3%) were lost to follow-up. Conclusions: Infective endocarditis, a disease especially of young adults and mainly caused by Streptococcus spp., was associated with rheumatic heart disease and had high mortality in Laos. (C) 2014 The Authors. Published by Elsevier Ireland Ltd.