The 1981 Davis Cup (also known as the 1981 Davis Cup by NEC for sponsorship purposes) was the 70th edition of the Davis Cup, the most important tournament between national teams in men's tennis. 53 teams would enter the competition, 16 in the World Group, 23 in the Europe Zone, 8 in the Americas Zone, and 6 in the Eastern Zone.
The 1981 tournament marked the introduction of the 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 Zonal semifinals chosen to compete in the inaugural bracket. Teams which lost in the World Group first round would now compete against each other in the World Group Relegation Play-off, with the four losers relegated to their respective Zonal competition the following year. The four winners of the Zonal competitions would now earn promotion into the following year's World Group to replace the relegated teams.[3][4]
This year also marked the first year of commercial sponsorship, when Japanese electronics company NEC became the tournament's first Title Sponsor, a partnership that lasted 21 years in total. NEC's partnership also enabled prize money to be given for the first time, with the World Group team competing for a total of US$1 million.[3][4][5]