When freewriting has been applied somewhat commonly in foreign tertiary context, it is found to be a challenging technique for most Vietnamese high school teachers. Since freewriting has been claimed to bring to students numerous benefits regarding their writing performance and learning motivation, the issue is worth conducting in high school context. The current study was conducted with 62 tenth graders in a high school in Ca Mau to investigate the effects of freewriting on their writing performance and their perception toward using it in learning how to write. Data were collected from students’ pre- and posttest of writing and a questionnaire. The study results reveal some useful implications for teaching writing to high school students in remote areas of Vietnam where students lack both learning conditions and English language exposure.