This study aims briefly at describing and analyzing some aspects of Case endings in Standard Arabic. This is because that Case seems to play a significant role in the grammar of not only Arabic but also in the grammar of many other languages. Many readers of this study might be wondering what Case is and why it is being dealt with. In order to comprehend the notion of Case in Arabic, it is necessary to consider the language in which word order is not as stable as it is in the case of English. In Arabic, an NP must have one of three Cases: nominative (NOM), accusative (ACC), or genitive (GEN) according to its position in a sentence. Many learners of Arabic as native or foreign speakers of the language may have no clear idea about Case system in the language. The rules of Case help these learners understand the proper structure of the language. Therefore, a distinction between three types of Case, i.e., Nominative Case, Accusative Case and Genitive Case, is to be dealt with for Arabic lexical NPs.