The present study was an attempt to explore the effectiveness of the functional approach to foreign language instruction in acquiring grammatical accuracy in comparison to structural approach which is based on rule- orientated techniques rather than meaning and interaction- oriented ones. To that end, 70 participants majoring in English language translation at the University of Islamic Azad University of Tonekabon in Iran were randomly selected. The research followed the qualitative and quantitative research methods to evoke the required data. The collected data was statistically analyzed through paired sample t-test. Overall, results showed that the functional approach to second language instruction is more effective in acquiring the grammatical accuracy than the structural approach. Pedagogical Implications of the study are further discussed. Key Words: Functional Approach, Structural Approach, Grammatical Accuracy.