Long line or longline may refer to:

• Long Line, an album by Peter Wolf
• Long line (topology), or Alexandroff line, a topological space
• Long line (telecommunications), a transmission line in a long-distance communications network
• Longline fishing, a commercial fishing technique
• AT&T Long Lines, a telecommunications network
• AT&T Long Lines Building, now known as 33 Thomas Street, a building in New York City
• Aerial crane or longline, a transport method
• Peripherally inserted central catheter, a medical device