Bosentan has proven 4-month efficacy in patients with HIV-associated pulmonary arterial hypertension (PAH-HIV). Herein, the long-term outcome of unselected PAH-HIV patients treated with first-line bosentan is described. Data for 59 consecutive World Health Organization (WHO) functional class II-IV PAH-HIV patients treated with first-line bosentan between May 2002 and July 2007 were analysed. HIV status, 6-min walk distance and haemodynamics were assessed at baseline, after 4 months and every 6-12 months thereafter. After 4 months, 6-min walk distance increased from 358+/-98 to 435+/-89 m and pulmonary vascular resistance decreased from 737+/-328 to 476+/-302 dyn x s x cm(-5). At the final evaluation (29+/-15 months), 6-min walk distance remained stable and pulmonary vascular resistance decreased further to 444+/-356 dyn x s x cm(-5). Haemodynamics normalised in 10 patients. At their last evaluation, these 10 patients were in WHO functional class I, with a 6-min walk distance of 532+/-52 m. Overall survival estimates were 93, 86 and 66% at 1, 2 and 3 yrs, respectively. Bosentan was safe when combined with highly active antiretroviral therapy, with no negative impact on HIV infection control. The present data confirm the long-term benefits of bosentan therapy in HIV-associated pulmonary arterial hypertension patients with improvements in symptoms, 6-min walk distance and haemodynamics, and with favourable overall survival.