Pulmonary arterial hypertension (PAH) is one of the long-term complications of HIV infection. The incidence of HIV-PAH is estimated at 0.5% of HIV-infected individuals. The mechanism by which infection leads to full-blown PAH is unknown. We describe a 44-year-old female patient with HIV infection diagnosed in 2004. Pulmonary hypertension was diagnosed in 2006. Seven months after the first cardiovascular clinical signs had started, the patient was referred to hospital because she was in New York Heart Association functional class IV. She commenced treatment with sildenafil. After increasing the sildenafil dose to ensure therapeutic drug levels over 24 h, the PAH and physical performance of the patient improved significantly. Our experience confirms long-term benefits of sildenafil monotherapy in PAH-HIV adult patients with improvements in symptoms and echocardiographic findings.