Actually, acronyms are not studied or written about thoroughly in Arabic and there is no enough elaboration on it in the students English textbooks. This study aims at investigating acronyms in English and Arabic, identifying, analyzing the errors that the university students are liable to make, and discovering the reasons beyond their errors. A diagnostic test applied to Translation students at the University of Mustansiriya. It is concluded that: (1) the achievement of the students in the English acronyms is better than their achievements in Arabic ones, (2) most of the university students can construct acronyms but they face more difficulties in discerning the words from which acronyms are constructed in English, (3) their performance is generally bad in both English and Arabic, and (4) some of the acronyms that are used in Arabic are borrowed from English without translation, while most others are translated into Arabic and written in their full forms without using acronyms.