Who may swim in a relay, and can the team be changed?
I · Intermediate · The event · 1 of 7A relay team has four swimmers, and each may swim only once in a race. The team leader names the order before a deadline set by the organisers. After that a swimmer can be replaced only for a proven medical emergency and with permission. Between the heats and the final, the team may be changed freely.
How it works
- Four: "Each relay team must be comprised of four (4) Athletes".
- Mixed: a team in a mixed relay "must be comprised of two (2) men and two (2) women".
- The order: the team leader must specify it before the race, by the deadline the management committee sets.
- After the deadline: a substitution may be made "only in the case of an evidenced medical emergency" and with the prior permission of the referee, the technical delegate or the management committee.
- Between rounds: "The composition of a relay team may be changed between the heats and finals of an event, provided that all relay team members are eligible".
- Once each: "An Athlete may compete in a race only once as a relay team member."
- Staying out of the water: a team member who is not next to swim must not enter or re-enter the water until every team has finished.
- Getting out: a swimmer who has finished their leg must leave the pool as soon as possible without getting in the way of anyone still swimming.
- The penalty: a breach of any of these disqualifies the relay team.
Tricky cases
Can a team use four different swimmers in the final from those who swam the heat?
Yes. The composition may be changed between heats and finals if all the swimmers are eligible for the relay.
A swimmer feels unwell an hour before the race, after the order was handed in. Can they be replaced?
It depends on the evidence and on permission. A substitution after the deadline needs an evidenced medical emergency and prior approval.
A swimmer who has finished their leg jumps back in to celebrate before the last team has touched. What happens?
The relay team is disqualified. A team member may not re-enter the water before all athletes have completed the distance.
Can the swimmers go in a different order from the one handed in?
No. The order specified by the team leader is the order in which they must compete.
Why the rule exists
Naming the order in advance lets officials check that the right swimmer is on the platform, and in a mixed or medley relay that the team is properly made up. Letting teams change between heats and final is what allows a country to rest its fastest swimmers in the morning.
Where it differs
| Where | What changes | Source |
|---|---|---|
| World Aquatics rules | As above | SW 10.4.1 to 10.4.3; SW 10.4.6; SW 10.4.7; SW 10.5 |
| Records | All four members must have the same sport nationality | SW 12.3.3 |
| Seeding | Relay teams are put into heats and lanes like individual swimmers | SW 3.2.6 |
From the rule book
World Aquatics, Competition Regulations, Part Two: Swimming Rules (in force as from February 2026), Articles 10.4 and 10.5. Checked 14 October 2026. Official document: World Aquatics Competition Regulations (PDF).