Flexibility in design is one of the sustainability techniques in architecture which applying it shall increase any buildings sustainability and life expectancy. Hospital buildings are the most type of buildings that needs that due to the rapid and frequent changes that happens to the hospital buildings architecture. High specialized departments in specific, needs flexibility more than other departments to cope with the huge load and development in it. ICU department as one of the specialized departments will definitely increase its sustainability if applied flexibility guidelines on it. Flexibility is the ability to change with an ease and without affect any of the other element badly, it has certain guidelines that guides the way to apply flexibility in hospital buildings