Where one of the parties of contract has the right to terminate it in accordance with defect, loss, fraud, incorrect description and option (khiar), he is bound to apply his right according to the articles of 415, 420, 435 and 440 Civil Act immediately and without delay, otherwise he will lose it. In these cases, the reflect able question is that what the meaning of termination urgency is, in other words, how much is the moratorium of application of the termination right and when does this start? This article surveys firstly the above- mentioned questions in Iranian legal system in detail and then studies briefly the answer of the British legal system as well as the Convention of Interactional Sale of Goods (Vienna - 1980).The results of this study showed that despite that the studied legal systems suggest the delivering date of goods as of the starting point of termination right, in Iranian law, urgency is considered when the holder of the right is aware of the cause of the termination right, whether the goods is delivered or not. Still there are so many who believe that not only the awareness of the cause of the termination but also being aware of the order of termination and its urgency is obligatory.