PNA or Pna has a variety of meanings:

• abbreviation for orchid genus Paphinia
• Pacific–North American teleconnection pattern, a climatic phenomenon
• Parisiensia Nomina Anatomica, the revision of anatomic nomenclature
• Peanut agglutinin, a lectin specific for Gal-β(1–3)-GalNAc
• Peptide nucleic acid, an artificially synthesized polymer similar to DNA or RNA.
• Plastic neutral axis, an engineering value used in plastic section modulus
• Pottery Neolithic A, a division of the Pottery Neolithic period in archaeology

• Pakistan National Alliance
• Palestinian National Authority, an administrative autonomous government in parts of the West Bank and the Gaza Strip
• Partido Nacional Agrarista (National Agrarian Party), a Mexican left-wing agrarian political party founded in 1920
• Partidul Național-Agrar (National Agrarian Party), a Romanian right-wing agrarian political party active in the 1930s
• Project for Nuclear Awareness, a non-profit organization that advocates for the abolition of nuclear weapons, co-founded by John C. Haas
• Polish National Alliance, a non-profit organization, the largest Polish – American Fraternal Benefit Society in USA offering life insurance and annuities. Founded in 1880, operates solely for the benefit of its members.
• Pa-O National Army
• Partido Nueva Alianza, the Spanish name for the New Alliance Party (Mexico)
• Parties to the Nauru Agreement
• Pennsylvania NewsMedia Association
• Philippine Nurses Association
• Prefectura Naval Argentina, the Spanish name for the Argentine Naval Prefecture
• National Anticorruption Directorate, Romania; formerly, National Anticorruption Prosecution Office (PNA)

• HomePNA, a home-computer networking standard
• Personal navigation assistant (PNA)

• Pacific Northern Airlines, acquired by Western Airlines in 1967
• Pamplona Airport
• Partial nail avulsion, a treatment of ingrown toenails
• Philippine News Agency
• Prenuptial agreement, a marriage contract

• PNAS, Proceedings of the National Academy of Sciences of the United States of America
• PnaS, Phosphate-Sodium Symporter, a sodium/phosphate cotransporter
• Protected Natural Area (disambiguation)