Pulmonary arterial hypertension (PAH) can be prevented in persons susceptible to the diseases and PAH patients can be treated by administering an effective dose of a leukotriene inhibitor. Suitable inhibitors include leukotriene A4 hydrolase (LTA4H) inhibitors, leukotriene B4 receptor (BLT1/BLT2) antagonists, 5-lipoxygenase (5-LO) inhibitors, and 5-lipoxygenase activating protein (FLAP) inhibitors.