Who holds the record for the fastest recorded serve in tennis?

Sam Groth holds the record for the fastest recorded serve in tennis, measured at 263.4 km/h (163.7 mph) at an ATP Challenger event in Busan, South Korea, in 2012.

Groth produced the serve during a match against Belarusian Uladzimir Ignatik. The speed was extraordinary, but the record came at Challenger level rather than on the main ATP Tour. That distinction explains why other names sometimes appear in answers to this question.

John Isner recorded a 253 km/h (157.2 mph) serve at the 2016 Davis Cup, making it the fastest serve officially recognized in an ATP-level competition at the time. Ivo Karlović’s 251 km/h (156 mph) serve was another major benchmark, while Andy Roddick’s 249 km/h (155 mph) serve was the previous widely cited ATP record.

The wording “recorded serve” is important: it includes the fastest measured serve in professional tennis, not merely the fastest serve at an ATP Tour tournament. Groth’s mark is therefore the canonical answer, although quiz questions that say “official ATP record” may point to a different player.