The Weak two bid is a common treatment used in the game of contract bridge to signify a weak hand with a long suit. It is a form of preemptive bid. Most often, the term refers to an opening bid; there is also a "weak jump overcall", which denotes a similar type of hand, but bid over an opponent's opening bid.

The requirements for a weak two bid vary from pair to pair. The most common treatment is that it requires:

• an exactly six-card good suit (the definition of "good" being subject to interpretation)
• no more than one Ace or King in other suits
• no side 5-card suit or 4-card major
• about 6-11 high card points total.

For example, the American Contract Bridge League recommends that the opener hold at least two of the top three cards in the suit, and hold no outside ace. Others recommend no more than eleven points, or at least three honors.

In Charles Goren's original bidding system, when a player opened the bidding with two of a suit, this signified that the player held a very strong hand. (This later became known as the strong two bid.) Later players found it more effective to reserve only the conventional opening 2♣ to show a strong hand. That left the room for opening bids of 2♦, 2♥, or 2♠ to show a weak hand with a six-card suit. This became known as the weak two bid. In some systems, a bid of 2♣ shows a strong hand with a five-card suit, and a bid of 2♦ shows a hand that is similarly strong, but balanced. These alternate versions are less common.

Responses to a weak two opening bid are limited. A single raise of the bid suit is either invitational or preemptive, a raise to game is to play. A bid of any other suit asks the bidder to support the suit with 2 or more card support or rebid the original suit. A bid of 2NT is forcing for one round and may ask the opener to show an outside feature such as an Ace, a King, or a void, or to give a coded response as to the strength of his suit and hand (the Ogust convention). The meaning of any of these bids should be discussed by the partners prior to play.