The present invention describes methods for using Treprostinil or its derivative, or a pharmaceutically acceptable salt thereof, for the treatment and/or prevention of interstitial lung disease or asthma, or a condition, such as pulmonary fibrosis, associated with interstitial lung disease or a condition associated with asthma. The invention also relates to kits for treatment and/or prevention of such condition that include an effective amount of Treprostinil or its derivative, or a pharmaceutically acceptable salt thereof.