English immersion has become a highly-acclaimed medium of instruction in South Korea, not only for English language education but content-based instruction. The international high school curriculum in South Korea, instructed by way of English immersion, and the effects of English immersion on students` production, have also been spotlighted recently. This study was designed to investigate the effects of English immersion on L2 writing of personal narratives. By performing a narrative task L2 learners demonstrate their writing skills and styles in their L2. And by comparing international high school students` and general high school students` written discourse curricular differences in the use of narrative structural features may be demonstrated. The findings revealed that significant group differences are found in narrative length, events, duratives, evaluation and complicating actions. However, with regard to the proportion ofnarrative length, few significant differences regarding the narrative structure and evaluative devices were found between the two groups. The findings suggests that both groups` students preferred structural elements that are similar, even though international high school students have been more exposed to the target language and its culture. However, compared with general high school students, international high school students endeavored to develop the high point of the story by producing more clauses in their narratives. The results may be used to judge or guide the further study of L2 students` discourse competence as well as to guide L2 writing instruction. (Korea University).