The 2005 St. Petersburg Open was a tennis tournament played on indoor hard courts.

It was the 11th edition of the St. Petersburg Open, and was part of the International Series of the 2005 ATP Tour.

8, Australian Open quarterfinalist, French Open semifinalist, St. Pölten winner Nikolay Davydenko, Wimbledon semifinalist, 1997 St. Petersburg champion Thomas Johansson, and Memphis and Nottingham titlist Max Mirnyi.

Also competing were Cincinnati Masters quarterfinalist Mikhail Youzhny, Moscow runner-up Nicolas Kiefer, Jarkko Nieminen, Greg Rusedski and Fernando Verdasco.

Thomas Johansson defeated Nicolas Kiefer, 6–4, 6–2 Julian Knowle / Jürgen Melzer defeated Jonas Björkman / Max Mirnyi, 4–6, 7–5, 7–5