The purpose of this study was to examine the awareness level of the prolonged sound rules in elementary school students. The participants in this study were 148 elementary school students in grades 1 through 6. Their awareness level of the prolonged sound rules was evaluated on reading tasks composed of 40 words and sentences. An one-way ANOVA followed by Scheffe hoc tests showed the showed the statistically significant difference between the groups for the awareness level of prolonged sound rules. The younger the children, the larger differences in the awareness of prolonged sound rules. The awareness might affect their cognitive development and a systematic instruction may be helpful especially in lower graders. In conclusion, the findings of this study showed significant differences in the awareness level of the prolonged sound rules at both words and sentences level. It was also found that as the age of children increases, the awareness level of the prolonged sound rules tends to increase which appeared to be completed by the 3rd grade.