The Sokolsky Opening (also called the Orangutan or Polish opening) is an uncommon chess opening in which White opens with 1.b4 (see algebraic notation). Of the twenty possible first moves from White, 1.b4 ranks ninth in popularity. It is classified under the A00 code in the Encyclopedia of Chess Openings.

Black can respond in a variety of ways: perhaps the most principled is to make a claim to the centre (which White's first move ignores) with 1...d5 or 1...e5, though less ambitious moves like 1...Nf6 and 1...c6 are also reasonable. After 1.b4 e5 it is normal for White to ignore the attack on the b-pawn and play 2.Bb2, when 2...d6, 2...f6, and 2...Bxb4 are all playable.

The opening has never been popular at the top level, though a number of prominent players have employed it on occasion (for example, Richard Réti against Abraham Speijer in Scheveningen 1923 and Boris Spassky against Vasily Smyslov in the 1960 Moscow–Leningrad match). Perhaps its most famous use came in the game Tartakower–Maroczy, New York 1924; it is from this game that the name "Orangutan Opening" originates. (Tartakower had made a visit to the zoo and decided to dedicate his next game to an orangutan he saw there). One of its more persistent exponents was Alexey Sokolsky , whose name it often bears (though even Sokolsky more often played 1.c4, 1.d4, or 1.e4).