Omaha hands are played out in a similar fashion as those in Texas Holdem. However, instead of two down cards, four are dealt, followed by a betting round. A three card flop follows, with another betting round. Next comes an one card turn card, with a another betting round. Finally a fifth river card, and a final round of betting.

At the showdown, five card hands are created by using exactly two cards from a player’s hand, and exactly three cards from the board cards. All four of a player’s cards must be shown to qualify for winning a pot. If you only show two cards and discard the other two, your hand is dead and you forfeit claim to the pot.
The basic rules of Texas Hold’em apply, except the “use two cards from your hand” requirement means a player cannot “play the board” like in Texas Holdem. Regardless of what is on the board, without exception players must use three cards from the board and two from their hand. Even if there are five spades on the board, you must have two spades in your hand to have a flush.

Omaha High Low
Omaha games are often played High/low split, with and eight-or-better qualifier for low. Players may use two different cards from their hand to make a low, and two different hand cards to make a high, as well as three different board cards to make their high hand and three different ones to make their low hand. The can also use the same three card/two card combination to make both their high and low hands.
All the rules of Omaha High apply to Omaha HiLo split except the eight-or-better for low applies (unless a cardroom has non-standard rules about what wins for low, like a nine-or-better for low rule). If no qualifying low hand exists, the winning high hand takes the whole pot. In some casinos, when a player wins an entire pot of a certain size, a kill must remain in the pot.
Reading a Low Hand
Low hands range from the worst possible low hand, 87654, to the best possible low, 54321. The simplest way to judge the best low hand possible in any given hand is the read the hands as a number, highest card to the left and lowest card to the right. Whichever number is lower wins: 76543 beats 84321.
Cards Speak
The Cards Speak rule applies. If a player mistakenly verbally declares an incorrect value of a hand, it does not matter what the player says. The casino dealer should read what the actual value of a player’s hand is.