Although pulmonary endarterectomy remains the treatment of choice for patients with chronic thromboembolic pulmonary hypertension (CTEPH), not all patients will benefit from or receive this highly specialised surgery. Patients whose CTEPH is deemed inoperable by an experienced centre and patients with persistent pulmonary hypertension after surgery are candidates for trial of pulmonary arterial hypertension (PAH) specific pharmacotherapies. However, the currently available PAH specific pharmacotherapies have not demonstrated a clear benefit in either of these patient groups. Accordingly, PAH therapies remain off-label for use in CTEPH. Riociguat (BAY 63-2521) is a stimulator of soluble guanylate cyclase, and may represent a novel agent in the treatment of select patients with CTEPH. Pre-clinical and human phase II studies with riociguat have reported promising results, and a multinational, randomised, controlled, double-blinded phase III study is currently underway to investigate the effect of riociguat in patients with inoperable CTEPH and those with persistent or recurrent pulmonary hypertension following pulmonary endarterectomy.