PEM may stand for:
- Peabody Essex Museum
- Pediatric emergency medicine
- Photoelastic modulator
- Polioencephalomalacia
- Polyelectrolyte multilayer
- Porous European Mix – a type of asphalt used on roads and airport runways, commonly referred to as PEM
- Portable Emissions Measurement System (PEMS)
- Predictive Emission Monitoring System (PEMS)
- Positron emission mammography
- Power Entry Module
- Privacy Enhanced Mail
- the .pem filename extension is used for a Base64-encoded X.509 certificate
- Protein-energy malnutrition
- Proton exchange membrane or Polymer Electrolyte Membrane – as in "fuel cell", applications include use in proton-exchange fuel cells, used to manipulate hydrogen for energy conversion
- The IATA code for the Padre Aldamiz International Airport in Puerto Maldonado, Madre de Dios, Peru
- Pemberton railway station, England; National Rail station code PEM
- Puritanical Euphoric Misanthropia
- PEM nut Self Clinching nut - commonly referred to as 'PEM'