PDI may refer to:
Organizations Investigations Police of Chile () Party for Justice and Integration (), an Albanian political party Pacific Data Images (1980-2015), an American computer animation company Paul Drude Institute for solid state electronics, German research institute Philippine Daily Inquirer, a newspaper Plumbing & Drainage Institute, US Ideal Democratic Party, political party in Rwanda Partai Demokrasi Indonesia (Indonesian Democratic Party) (1973–2004), a defunct political party Polo Democrático Independiente (Independent Democratic Pole), a Colombian democratic political party
Chemistry and biochemistry Pyridinediimine, organic compounds used as ligands Perylenediimide, a rylene dye Photodynamic inactivation, or antimicrobial photodynamic therapy Protein dispersibility index, in water Protein disulfide isomerase, an enzyme Polydispersity index, molecular weight distribution of polymers Pentamethylene diisocyanate, a bio-based diisocyanate prepared from pentamethylene diamine
Computing Pentaho Data Integration, design data flow software Versit Consortium's Personal Data Interchange Pop Directional Isolate, Unicode bidirectional text character Portable Database Image format (.pdi) Atmel Program and Debug Interface
Other Pacific Deterrence Initiative, a deterrence framework by the United States Department of Defense Postal Development Indicator, a UPU ranking Peripheral drift illusion, a motion illusion Pilot direction indicator, for aircraft bombing Power Distance Index, a measure of social power acceptance Powered Descent Initiation, of Apollo moon landing