Pulmonary hypertension (PH) is a frequent complication of left heart disease arising from a wide range of cardiac disorders. In the clinical classification, PH associated with left heart disease is classified as Group 2, which includes left heart systolic dysfunction, left heart diastolic dysfunction and left heart valvular disease. In the past, rheumatic mitral valve disease was the most common cause of PH in left heart disease; however, today it is more likely to be associated with hypertensive and/or ischaemic heart disease. As the incidence of these conditions is increasing, the number of patients presenting with PH is also increasing and, today, left heart disease represents the most frequent cause of PH. The development of PH in patients with left heart disease is associated with poor prognosis. However, despite the increasingly large number of patients affected and the impact of PH on outcome, there are currently no specific treatment options for these patients. This review gives an overview of the pathophysiology and epidemiology of PH associated with left heart disease, and discusses the challenges associated with its management and treatment.