This study investigated the linguistic errors made by Omani EFL students in their written essays at a discourse level. A descriptive method of research was utilized to gather information from twenty-five EFL undergraduate students’ essays selected purposively to identify the linguistic errors from an error analysis viewpoint. The result shows that there are 15 linguistic errors found in the student’s essays which are caused by interlingual and intralingual interferences. The result also exhibited that of 15 linguistics errors, spelling (88%), capitalization (80%), and punctuation errors (72%) are the most serious. This indicates that these errors are mechanical in nature which is the topmost errors with 51.12% when grouped into classification of errors due to the influence of mother tongue. It implies that participants’ mother tongue (L1) contributed a lot to the mechanical errors committed. It can be gleaned that the participants are ignorant of the rule restrictions on the proper use of punctuation and capitalization as well as the rules on how to write the words correctly.