PTR
PTR can refer to:

 Particle transfer roller, for cleaning motion picture film
 Peak-to-trough ratio, a parameter in pharmacokinetics
 Petir LRT station (LRT station abbreviation), Singapore
 PetroChina (NYSE: PTR)
 Photothermal Ratio, light/temperature ratio for a plant
 Physical transmission right in the electricity market
 Physikalisch-Technische Reichsanstalt, later Physikalisch-Technische Bundesanstalt, a German research institute
 Pitrilysin, an enzyme
 Planar ternary ring in algebra
 Pool Test Reactor, Canada
 Proton-transfer-reaction mass spectrometry, used in chemical analysis
 PTR rifle, made by PTR Industries, Inc., US
 A type of DNS record in computer networking
 Pointer in computer programming (e.g. the PTR keyword in x86 assembly language)
 Palanivel Thiagarajan, an Indian politician
 Puerto Rico, ITU country code
 Public Test Realm, a server in Overwatch where updates are tested by developers for player feedback