Sections 8 and 9 of the Sale of Goods Act of United Kingdom (SGA 1979) and Article 55 of the United Nations Convention on Contracts for International Sale of Goods (CISG) provide the rules on open price term in contracts for the sale of goods. The concept of open price was created following new circumstances in the global trade, necessities and needs of humankind. However, changes in the rules should be compatible with these new needs. Good rules are those that not only have been initially formed and drafted in a wise and precise manner, but also have been amended based on the shortcomings that it may have in practice. Otherwise, it would be a repetition of negligence of legislators each time that a weak, un-amended rule is performed. Since the enactment of the SGA 1979, which is a copy of its preceding provisions in SGA 1893, it has not reviewed or amended. This is the same with the provisions of the CISG. Thus, in this paper, through a doctrinal type of research and a comparative, analytical and critical approach to the issue, a library based study has been performed on SGA 1979 and the CISG. The aim of this paper is to highlight the salient aspects of the open price provisions in SGA 1979 and CISG in order to propose the necessity of their amendment.