Objective: The present study was conducted to analyze and compare the written discourse of EMR students according to textual metafuntion introduce- ed in Halliday’s systemic functional grammar. Method: The present research follows a descriptive method. The informants (311 students) were chosen among the primary, prevocational guidance school and vocational high school students in 2009. The informants were chosen according to multi-stratified cluster sampling. Four schools have been selected through random-sampling (two for boys and two for girls). A written test in the form of picture stories was administered to 311 students. Results: At first, the data (consisted of 2407 clauses and 10861 words) were analyzed concerning the thematic structure in clauses. Concerning the textual metafunction, overt subject theme is the most frequent (61%) in all grades. Covert subject theme occurred in (34%), and textual theme in (23%) of the clauses. The frequency of covert subject theme increases as the grades increase. Complex theme happens in about 25% of the clauses. Additionally, 96% of complex themes consist of textual and topical themes. Interpersonal themes come after textual and before topical themes. Conclusion: Nonparametric statistical test (x² test) shows that the difference between EMR students' use of different theme (except object theme) in different grades is significant when P≤0/001. Moreover, the use of different themes in each grade is also significant. The frequency of complex theme (as a criterion of complex clause) increases as the grade increases.