MTA can refer to one of several subjects (with the most common referents emphasized):

• the Hungarian Academy of Sciences (Magyar Tudományos Akadémia)
• a mail transfer agent in computing
• the Maryland Transit Administration, which governs Baltimore's mass transit
• Metropolitan Transit Authority, a body that governs a city's mass transit
• Metropolitan Transportation Authority, a body that governs a city's mass transit
• the Montreal Transhumanist Association
• Mount Allison University, Sackville, New Brunswick
• The MTA Song, a folk song
• Multi Theft Auto, a Grand Theft Auto: Vice City mod
• the Municipal Transportation Agency, the body that governs San Francisco's mass transit, parking, and traffic functions