Miss Universe 2001 was the 50th anniversary of the Miss Universe pageant, held at the Coliseo Rubén Rodríguez in Bayamón, Puerto Rico, on May 11, 2001.

At the conclusion of the event, Lara Dutta of India crowned Denise Quiñones of Puerto Rico as Miss Universe 2001. This was Puerto Rico's fourth win in the history of the pageant.

Contestants from seventy-seven countries competed in this pageant. The competition was hosted by Elle Macpherson and Naomi Campbell. Todd Newton acted as backstage correspondent, while Miss Universe 1997 Brook Lee provided commentary for the whole event. Ricky Martin and La Ley performed in this edition.

After twenty-nine years, the Miss Universe pageant returned to San Juan to hold its 50th edition on May 11, 2001. According to Puerto Rico's tourism director, Jorge Pesquera, the final telecast of the competition will help promote the territory to potential tourists.

Seventy-seven countries and territories competed in the pageant. Three candidates were appointed to their position to replace the original winner.

Poland was to be represented by the first runner-up of Miss Polonia, Malgorzata Rozniecka. However, studies prevented her from attending, and the organization replaced her with Monika Gruda. The organization invited Miss Russia 2001, Oxana Fedorova, to attend the pageant, but was unable to compete due to her studies. She was replaced by first runner-up, Oxana Kalandyrets, who reached the top 10. Fedorova would go on to win the following year's Miss Universe pageant, only to be replaced with her runner-up four months later.

Miss Spain 2001, Lorena van Heerde Ayala, was unable to compete as she was underage. She was replaced by first runner-up, Eva Sisó. Ayala was due to compete in Miss Universe 2002, but after the threat of lawsuit by her family against the Miss España Organization for breach of contract, she cut all ties with the Miss España organization and lost the right to represent Spain at any international pageant.

This edition marked the debut of Slovenia; and the returns of Antigua and Barbuda who last competed in 1979; and Curaçao, Nicaragua, the Northern Mariana Islands, Turkey, and the United States Virgin Islands who last competed in 1999. Australia, Belize, Denmark, Great Britain, Guam, Hong Kong, Mauritius, Namibia and Sint Maarten withdrew after their respective organizations failed to hold a national competition or appoint a delegate. Phan Thu Ngân of Vietnam got married and refused to compete in Miss Universe 2001.