This subject of the research is language problems faced by Islamic Studies students at two Malaysian universities, KUlM and UIAM. The research aims to identify and analyze the most common mistakes made by KUIM and UIAM Islam~c S~udies students in written Arabic. The research consists of two parts. The first part delves into the theories that explain how and why students make mistakes when writing in Arabic. The second part of the research consists of data analysis. A sample of a group of students' final year examinations is used to analyze and identify the most common mistakes in the writing of Arabic. The research indicates that the most common mistakes in written Arabic include the following: the misuse of the symbol Irab Usul and Furuk, the usage of AIi Lam Takrlf; penyelarasan kategori jantina, the use of the letter jar, and the use of pronouns, Aid after Isim Mausul. The research also revealed that the students' background contributes to the occurrence of common mistakes in examinations. The research suggests that the curriculum and syllabus for the teaching of Arabic need to be improved. Specific suggestions for improving the students' mastery of Arabic are also provided in this research.