1999 US Open – Boys' singles

David Nalbandian was the defending champion, but did not compete this year.

Finnish player Jarkko Nieminen defeated Danish first seed Kristian Pless in the all-Nordic final, 6–7, 6–3, 6–4.

Seeds

 * 1)  Kristian Pless (final)
 * 2)  Irakli Labadze (quarterfinals)
 * 3) 🇦🇷 José Acasuso (second round)
 * 4) 🇹🇭 Danai Udomchoke (third round)
 * 5) 🇦🇷 Guillermo Coria (second round)
 * 6) 🇫🇷 Éric Prodon (first round)
 * 7) 🇫🇮 Jarkko Nieminen (champion)
 * 8) 🇺🇸 Phillip King (quarterfinals)
 * 9) 🇧🇬 Todor Enev (third round)
 * 10) 🇺🇸 Mardy Fish (quarterfinals)
 * 11) 🇸🇪 Joachim Johansson (first round)
 * 12) 🇫🇷 Nicolas Mahut (semifinals)
 * 13) 🇺🇸 Andy Roddick (first round)
 * 14) 🇩🇪 Maximillian Abel (third round)
 * 15) 🇺🇸 Levar Harper-Griffith (third round)
 * 16)  Mario Ančić (second round)