‘Straight flush’ is among the strongest combinations a poker player may have in a poker card game. In Vietnam, to understand how to play better and relevant rules, a player needs to understand the ‘straight flush rule’ – the rule of the game when there is a straight flush on the table. According to general rules, ‘straight flush’ is a combination of a five straight sequence of card of the same suits. A poker ‘straight flush rule’, however, clearly states the order of the hands and winning conditions. ‘Straight flush’ is one of the best hands players can have in poker, although second to ‘royal flush’. In Vietnam, casinos and betting sites players are required to understand the ‘straight flush rule’ to avoid mistakes and confusion. More specifically, the rule helps to understand which player wins in case there are multiple ‘straight flush’ hands on the table. Understanding ‘straight flush rule’ helps players avoid mistakes and increase a winning possibility. In summary, knowledge of ‘straight flush’ and relevant rules is ultimately essential for poker playing in Vietnam.