1981 Grand Prix (tennis)

The 1981 Grand Prix was a men's professional tennis circuit organized by the International Tennis Federation (ITF). It was the 12th edition of the Grand Prix tennis circuit. It comprised the four Grand Slam tournaments, the Grand Prix tournaments (divided into designated categories), the World Team Cup, and the year-end Masters Grand Prix.

The designated tournaments were those tournaments that awarded points towards the year-end bonus pool and Masters Grand Prix qualification. These categories, in descending order of importance and points awarded, were: Volvo Grand Prix, Grand Prix, and smaller Grand Prix events.

Björn Borg was the defending Grand Prix champion, but he only played a limited schedule in 1981. John McEnroe won the 1981 Grand Prix title, finishing the year with the most points accumulated from tournaments throughout the season. The Masters Grand Prix was won by Ivan Lendl.

The Grand Prix tournaments formed the primary ranking system for male tennis players prior to the introduction of the ATP rankings in 1973, and continued to be a significant ranking system until the full adoption of the ATP rankings. Performance in Grand Prix tournaments, along with Grand Slam results, determined eligibility for the year-end Masters tournament. The circuit provided a structure and competitive environment for professional tennis, influencing the careers of many prominent players.