Previous studies examined benefits of collaborative writing, but the effectiveness of collaborative planning in academic writing courses has not been adequately addressed. Thus, this study examined Chinese-speaking ESL pre-university students' perceptions of the effectiveness of collaborative planning in an academic writing course in the Malaysian ESL context. This study is a qualitative research study in which data were collected using journal writing. The students in an academic writing course were requested to keep journals throughout the course. Specifically, they were requested to write about collaborative planning in terms of its effectiveness, challenges they faced, and suggestions for its improvement. Data were coded and analysed thematically. The analysis of the data revealed that Chinese-speaking ESL pre-university students perceived collaborative planning as an important instructional approach in which they could share ideas, develop their writing skills, and build their self-confidence. The study also showed that the students encountered some challenges, which resulted from their unfamiliarity with this approach. Suggestions for the improvement of collaborative planning given by the participants reveal that they enjoyed working collaboratively in groups at the planning stage of writing.