Pulmonary arterial hypertension (PAH) is a debilitating disease characterized by constriction in the diameter of the pulmonary arterial lumen.1,2 This leads to increased pressure and stress on the right ventricle of the heart, which may lead to heart failure and death.2,3 Currently there are only a few treatment options for patients with PAH. Sildenafil, a phosphodiesterase type 5 (PDE-5) inhibitor, can be used to treat PAH. Sildenafil inhibits the degradation of cyclic guanosine monophosphate (cGMP). Increased cGMP concentration results in pulmonary vasculature relaxation. Current clinical trials have indicated that sildenafil can significantly improve many of the symptoms of PAH. The trials have also shown that when used appropriately, sildenafil can be used with minimal side effects. It is important for pharmacists and other health care professionals to understand PAH as a disease state and its treatment options, such as sildenafil.