PPI may refer to:
Science and technology Biochemistry PPi, the anion P2O74−, a pyrophosphate Polyproline I helix Protein–protein interaction
Medicine Patient and public involvement Prepulse inhibition, of a later pulse Proton-pump inhibitor, a class of medications Psychopathic Personality Inventory, a personality test Psychophysiological Interaction, fMRI analysis technique
Computing Parallel Peripheral Interface, of the Blackfin processor Programmable Peripheral Interface, Intel 8255 chip Programmable Peripheral Interconnect, in Nordic nRF microcontrollers Pixels per inch, of a display Productivity Products International, commercializer of the Objective-C language
Other science and technology Gabarit passe-partout international, in railways Picks per inch, a unit of textile measurement Plan position indicator, radar display Polymethylene polyphenylene isocyanate
Business and organizations Italian People's Party (1919) (Partito Popolare Italiano), a political party Italian People's Party (1994) (Partito Popolare Italiano), a political party Payment protection insurance Peace Party of India, Uttar Pradesh Perusahaan Perdagangan Indonesia, trading company Philips Phonographische Industries, later Philips Records Phonographic Performance Ireland, music licensing company Pirate Parties International Polly Peck International, former UK company PPI Holdings, Inc., a Philippine franchisee of restaurant brands Primarily Primates, primate sanctuary, Texas, US Productivity Products International, US software company later renamed Stepstone Progressive Policy Institute, U.S. Pakistan Press International, a news agency
Other uses Pareto priority index, to prioritize projects Positive polarity item Producer price index Pulse Polio, immunisation campaign in India Port Pirie Airport, IATA airport code "PPI"