The 1990 Norstar Bank Hamlet Challenge Cup was a tennis tournament played on outdoor hard courts.

It was the 10th edition of the event (the first as a professional tournament and not an exhibition) known that year as the Norstar Bank Hamlet Challenge Cup, and was part of the ATP World Series of the 1990 ATP Tour.

1, Australian Open runner-up, Wimbledon champion, Indian Wells and Cincinnati titlist Stefan Edberg, French Open champion, Barcelona and Madrid winner Andrés Gómez, and Rotterdam and Orlando titlist Brad Gilbert.

Other seeded players were Philadelphia and Manchester winner Pete Sampras, Stuttgart titlist Goran Ivanišević, John McEnroe, Jonas Svensson and Guy Forget.

First-seeded Stefan Edberg won the singles title and earned $32,800 first-prize money.