The 4 × 100 metres relay or sprint relay is an athletics track event run in lanes over one lap of the track with four runners completing 100 meters each. The start is as for the 400 m. A baton must be passed within a 20 m changeover box marked by (usually yellow) lines 10 m before and after the start of each subsequent leg. The outgoing runner must not start behind a (usually orange) acceleration marker line 10 m further back.

A successful baton change requires the outgoing runner to be at (almost) full speed and arms length ahead of the incoming runner so there is little room for error. Outgoing runners normally mark the track with chalk or tape 6 to 8 m behind the acceleration line and set off flat out when the incoming runner reaches this mark. When inside the changeover box they will hold their hand back, and it is the incoming runner's responsibility to pass the baton. Runners on legs 1 and 3 run on the inside of the lane with the baton in their right hand, runners on legs 2 and 4 take the baton in their left hand.

Polished handovers can compensate for a lack of basic speed to some extent, and disqualification is common even at the highest level. Internationally, the United States men's teams have dominated this event, only ever failing because of poor baton changing. In the women's event, the US are currently (as of 2005) the strongest team following years of East German domination.

Events in athletics

4 × 100 m Staffel (Leichtathletik) | 4×100 m teatejooks | Relais 4 x 100 m hommes | 400メートルリレー走 | Sztafeta 4 x 100 m | 4 x 100 metrin viestijuoksu