1971 National Indoor Championships – Singles

The 1971 National Indoor Championships – Singles was an event of the 1971 National Indoor Championships tennis tournament held at the Hampton Roads Coliseum in Hampton, Virginia in the United States from March 1 through March 7, 1971. Stan Smith was the defending champion but did not take part in this edition. First-seeded Ilie Năstase won the singles title, defeating Ilie Năstase 7–5, 6–4, 7–6(5–0) in the final. Năstase had survived five match points during his semifinal match against Željko Franulović.