This research was aimed to find out the correlation between English grammar mastery and translation skill from Indonesian to English. It used correlational descriptive research which was conducted in English department of University of Muhammadiya Purwokerto academic year 2013/2014. The subjects of this research were 34 students of sixth semester of English department of University of Muhammadiyah Purwokerto. This research used test as data collection. The test was divided into two tests, first test was English grammar test and the second test was translation test. Then to analyze the data, this research used quantitative data, score test to know the value of each variable, mean, validity, reliability, product moment correlation and df formula.
The calculation showed some results. First, the students‟ grammar mastery was in good category with 80.73. Second, the students‟ translation skill was in good category with 71.05. Third, the correlation showed that the value of rxy was 0.77. Then, the r table value of 5% significance and N=34 was 0.34. therefore, the rxy > r table with 0.77 > 0.34. In conclusion, there was a positive and significant correlation between English grammar mastery and translation skill from Indonesian to English.