This research paper was conducted with the aim of determining the language proficiency of the students particularly in syntax and semantics and level of academic performance in Science subject, and the significant relationship between language proficiency and academic performance of the students. Descriptive-Quantitative Method has been utilized in this study to analyze and interpret the results. Researcher-made test was used to gather data. To interpret the data, Pearson-r moment of correlation was utilized to determine the significance of the hypothetical problem of the study. The findings revealed that the language proficiency of the students in terms of syntax and semantics is on beginning level leading to the hypothesis that there is significant relationship between the level of language proficiency and academic performance in science. The results signify that linguistic proficiency affects the academic performance of the students in science subject. In this regard, both teachers in English and Science subject could create tasks and activities where they can let the students master both skills in language use and knowledge in science. More so, integration of tasks is proposed to let the students accomplish more than one competency for both learning areas.