Introdução: A experiência com o fechamento percutâneo da comunicação interatrial (CIA) em crianças pequenas é limitada. Avaliamos a factibilidade, a segurança e a eficácia desse procedimento em crianças com peso < 20 kg. Métodos: Estudo descritivo observacional de uma coorte de crianças < 20 kg submetidas a tratamento percutâneo. Pacientes com dilatação ventricular direita e sintomas evidentes foram in cluídos. Implantamos próteses aprovadas pela ANVISA, sob monitorização ecocardiográfica transesofágica. Os pacientes foram avaliados 1 mês, 3 meses, 6 meses e 12 meses após. Resultados: Entre outubro de 1997 e maio de 2012, 80 pacien tes foram tratados. As medianas de idade e peso foram de 4 anos (112) e 13,5 kg (520), respectivamente, 20 pacientes apresentavam alguma síndrome genética (25%) e 4 pacien tes (5%) apresentavam CIA adicional. Somente um paciente necessitou duas próteses. Dois pacientes tinham defeitos ABSTRACT Background: The experience with percutaneous closure of atrial septal defect (ASD) in infants is limited. We sought to determine the feasibility, safety and efficacy of this procedure in children weighing < 20 kg. Methods: Observational study of a cohort of children weighing < 20 kg undergoing percutane ous closure. Patients with right ventricular enlargement and evident symptoms were included. ANVISA approved devices were implanted under transesophageal echocardiography moni toring. Patients were evaluated 1, 3, 6 and 12 months after the procedure. Results: Eighty patients were treated between October 1997 and May 2012. Median age and weight were 4 years (112) and 13.5 kg (520), respectively, 20 patients had a genetic syndrome (25%) and 4 patients (5%) had an additional ASD. Only one patient required 2 devices. Two patients had associated defects that were treated in the same procedure (pulmonary valve stenosis and arteriovenous fistula). One patient developed total atrioventricular block during device implantation, solved spontaneously 36 hours after de vice removal, with no need for pacemaker implantation. This patient was successfully treated percutaneously 6 months later