Pulmonary hypertension, including pulmonary arterial hypertension (PAH), is a serious disease in children, but few clinical studies have been conducted to evaluate treatment regimens in this population. Currently, treatment of children with PAH is mostly based on clinical studies conducted in adults and a few dedicated pediatric studies. Sildenafil, a phosphodiesterase type 5 inhibitor, has an established efficacy and safety profile for the treatment of adults with PAH. In May 2011, sildenafil received approval for the treatment of pediatric patients aged 1-17 years in the EU; however, pediatric use is not approved in the USA. This systematic literature review summarizes the clinical data available on the use of sildenafil to treat children with PAH and pulmonary hypertension.