A-line or A Line may refer to:
Transport
- A (New York City Subway service), rapid transit line
- A Line (Los Angeles Metro), rail line in Los Angeles
- A Line (RTD), commuter rail line between Denver and Aurora, Colorado
- Atlantic Coast Line Railroad, rail line in Florida
- A Line (Minnesota), a bus rapid transit line in Minneapolis, Saint Paul, and Roseville, Minnesota
- A-Line (Hamilton), planned rapid transit line in Hamilton, Ontario, Canada
- RapidRide A Line, bus route in King County, Washington
- Line A (Buenos Aires Underground), Argentina
- RER A, commuter rail line in Paris, France
- A (Los Angeles Railway), former streetcar service
Other uses
- A-line (clothing), a style of skirt or dress
- Arterial line, a thin catheter inserted into an artery
See also
- A-A line
- Aline (disambiguation)
- Line A (disambiguation)
- Line (disambiguation)