1981 Davis Cup World Group

The World Group was the highest level of Davis Cup competition in 1981. It was the first edition of the newly-formed 16-team World Group and a move to a tiered system including promotion and relegation. The original 16 teams to compete were chosen through the previous year's results, with teams that reached the 1980 Zonal semifinals chosen to compete in the inaugural bracket. The first-round losers would play in the Davis Cup World Group Relegation Play-offs, with the four losers relegated to their respective Zonal competitions the following year and replaced by the four winners of the current year's Zonal competitions.

Czechoslovakia were the defending champions, but were eliminated in the quarterfinals.

The United States won the title, defeating Argentina in the final, 3–1. The final was held at the Riverfront Coliseum in Cincinnati, Ohio, United States from 11 to 13 December. It was the US team's 27th Davis Cup title overall.

Relegation play-offs
The first-round losers played in the Relegation Play-offs. The winners of the play-offs advanced to the 1982 Davis Cup World Group, and the losers were relegated to their respective Zonal Regions.

Results summary
Date: 2–4 October


 * ,, and  remain in the World Group in 1982.
 * ,, and  are relegated to Zonal competition in 1982.