The 1991 ATP Tour World Championships was the men's tennis season-ending tournament. The singles event was also known as the IBM ATP Tour World Championships and was played on indoor carpet courts at the Festhalle Frankfurt in Germany. The doubles event, also known as the Standard Bank ATP Tour World Doubles Final, was played on indoor hard courts in held in Johannesburg, South Africa. Both competitions were held between 12 November and 17 November 1991. Sixth-seeded Pete Sampras won the singles title and John Fitzgerald with Anders Järryd won the doubles title.

Finals

Singles

🇺🇸 Pete Sampras defeated 🇺🇸 Jim Courier, 3–6, 7–6(7–5), 6–3, 6–4

Doubles

🇦🇺 John Fitzgerald / 🇸🇪 Anders Järryd defeated 🇺🇸 Ken Flach / 🇺🇸 Robert Seguso 6–4, 6–4, 2–6, 6–4.