PHA may mean:
- Phytohaemagglutinin, a type of lectin found in plants, especially beans
- Polycyclic aromatic hydrocarbons, a class of chemical compounds that consist of fused aromatic rings.
- Polyhydroxyalkanoate, biodegradable polymers produced by bacterial fermentation of sugar or lipids
- Polyhydroxyaldehyde, a class of carbohydrate
- Potentially hazardous asteroid, an asteroid with a size and an orbit such that it could potentially strike Earth
- Process Hazard Analysis, a systematic assessment of the potential hazards associated with an industrial process.
- Pulse Height Analyzer, a nuclear electronic instrument for sorting gamma rays or charged particles into bins by energy, counting them, and saving the spectrum of pulse heights obtained for further analysis.
- PHA training (Peripheral Heart Action Training), a form of bodybuilding circuit training
- Pakistan Housing Authority, organisation in Pakistan
- Parks and Horticulture Authority, an organisation in Lahore, Pakistan.
- Philadelphia Housing Authority
- Phoenix Hebrew Academy, a Jewish day school in north central Phoenix, Arizona
- President's House Association, a fraternity founded at Georgetown College (Kentucky)
- Private Hospitals Association (Jordan) is a private, voluntary, non-profit organization in Jordan, its members are some of private hospitals there.
- Public Housing Agencies, of the United States
- Pulmonary Hypertension Association, an educational support group for suffers of pulmonary hypertension
- Phoenix Sky Harbor International Airport, in Phoenix, Arizona (Amtrak station code: PHA)
- Amphoe Pha Khao, a district (amphoe) of Loei Province, northeastern Thailand
- Amphoe Phu Pha Man, the northwesternmost district (Amphoe) of Khon Kaen Province, northeastern Thailand
- Amphoe Tha Wang Pha, a district (Amphoe) in the central part of Nan Province, northern Thailand
- Amphoe Thong Pha Phum, is a district (Amphoe) in the northern part of Kanchanaburi Province, central Thailand
- Cẩm Phả, a town district of Quảng Ninh Province in the northeastern region of Vietnam
- Ko Pha Ngan, an island in the Gulf of Thailand in South East Thailand
- Pha Oudom District in Bokeo Province in north-western Laos
- Pha Taem, a national park in Thailand with famous rock art on its cliffs
- Pha That Luang, a Buddhist stupa in Vientiane, Laos
- Than Sadet-Ko Pha-Ngan National Park, a national park in southern Thailand
- Hso Khan Pha, a Consulting Geologist who lives in exile in Canada
- Jazze Pha (stage name Jazze Pha), an American record producer, songwriter, singer and rapper
- Jazze Pha production discography CD1 04
- Pha Terrell (1910-1945), an American jazz singer
- Anime Syuukan DX! Mi-Pha-Pu, a Japanese anime series
- Kuan pha na dum, the name of a folklore hero from Laotian mythology
- Pha Lai II Power Plant, one of Vietnam's largest coal-fired power plant
- Pha Lai Power Plant, one of Vietnam's largest coal-fired power plant