Despite the importance of phonological awareness in learning reading in the early stages of literacy, studies have shown that some students after the end of elementary education, and even some literate adults have poor phonological skills, that affects their reading. This study was a mixed methods one. The aim was to compare the adolescents' performance in syllabic, intra-syllabic and phonemic sub-tests and their relationship with reading comprehension. The qualitative part includes the review of theories and literature about phonological awareness and its relationship with reading comprehension, design of phonological awareness and reading comprehension tests, and examining their content validity. The quantitative part includes the implementation of the researcher-made tests on a sample of 30 students and calculating the reliability of tests (phonological awareness test (0.76) and reading comprehension test (0.80)). Then, the tests were distributed among a sample of 50 students from the 10th grade students of Lahijan. The results were analyzed using non-parametric Friedman and Wilcoxon tests and Spearman correlation test. The results showed that there is a significant difference between the performance of students at different levels of phonological awareness, as the best performance is related to the syllabic and the weakest is related to the intra-syllabic level. The results of Spearman correlation test showed that there is a high correlation between phonological awareness and reading comprehension (0.77). The results of this study can help educational programmers to design appropriate content to enhance the phonological awareness skills of students after elementary education.