Fare evasion, as distinct from fare avoidance, is the act of travelling on public transport in disregard of the law and/or regulation, having deliberately not purchased the required ticket to travel (having had the chance to do so). It is a problem in many parts of the world, and revenue protection officers operate on many systems. Often ticket barriers, manned or automatic, are in place at stations etc., to ensure only those with valid tickets may access the transport.

One method of fare evasion is jumping over the turnstiles which mark the entryway into a subway system; hence the term, "turnstile jumping". The most extreme method is train surfing.

Another method is on the bus, passengers would either bypass the bus driver or simply enter through the rear end of the bus. This is commonly found under the New York City Bus system which is causing its operators to lose millions of dollars a year.

Closed-circuit television (CCTV) monitoring is used by many public transport companies to combat vandalism and other public order crimes. Using CCTV to apprehend fare-dodgers in the act requires full-time human monitoring of the cameras. Sophisticated CCTV systems discriminate the scenes to detect and segregate suspicious behaviour from numerous screens and to enable automatic alerting. However, the attentiveness of the surveillance personnel may be threatened by false reliance on automatics.