What is a donk bet in poker?

A donk bet (or lead) is a bet made out of position into the player who had the initiative on the previous street, usually the preflop raiser. Example: the button raises preflop, you call from the big blind, and you bet first on the flop instead of checking to the raiser.

Why it’s usually a mistake

The preflop raiser has the stronger range on most flops, so they’d often bet anyway; checking lets them c-bet into you.
Donk betting medium hands often gets you raised off the best hand or called only by better hands.
Many beginners donk bet with weak made hands to “find out where they are”. It’s an expensive way to get information.

When a lead can make sense

Boards that favour the caller, such as low connected flops (7-6-5) when the raiser came from early position. The big blind has more two-pair and straight combos there.
On the turn, when the raiser checked back the flop (this is called a probe bet).
Against players who check behind too much: you’d miss value by checking.

These are more advanced ideas; checking to the raiser is a fine default for beginners.

How to play against donk bets

At low stakes, a donk bet is often a medium or weak hand. Raise with strong hands and good draws.
Call with hands that have showdown value; don’t fold too easily.
Watch for players who donk with monsters too and adjust.

See also check-raise and big blind defence.

FAQ

What is a donk bet in poker?

A bet made out of position into the player who had the initiative on the previous street.

Why is donk betting usually bad?

The preflop raiser often bets anyway, and leading with medium hands gets raised or called only by better hands.

When can a donk bet be good?

On boards that favour the caller, or on the turn after the raiser checked the flop (a probe bet).

How should you play against a donk bet?

At low stakes raise more with strong hands and draws, and don’t fold too easily.