Many of the students of the English Language & Communication (ELC) department at UCSI University are Malaysian Chinese (MC) students and International Chinese (IC) students from China. All the courses in the university are conducted in English. Currently, there is still lack of research done on grammatical errors among these students who possess the same first language but are from different nationalities. This study aims to investigate the grammatical errors in the IELTS essays written by 16 participants and were analysed using Error Analysis. These participants were divided into two groups namely, the IC students and the MC students to identify the types of grammatical errors made by these participants. The researcher then compared and contrasted the types and frequency of these grammatical errors between the two groups based on the Contrastive Analysis Hypothesis, Creative Construction Hypothesis and Interlanguage Theory. The findings showed that the types of grammatical errors made are mainly errors of omission, misformation, misuse, repetition, vocabulary, structure, coherence/cohesion, expression and misordering. Overall, the results indicated that the IC participants made more grammatical errors compared to the MC participants.