The purpose of this study was to know whether there is a significant
correlation between students’ grammar mastery and students’ writing ability on
descriptive text at the tenth grade students of SMK Muhammadiyah Majenang in
Academic Year 2016/2017. The subject of this research was 43 subjects. This
study used a correlational study. The writer used random sampling to get the
samples. In collecting the data, the researcher used grammar test and writing test.
Then, in analyzing the data, the researcher used product moment correlation. The
result of this study showed that there was a significant correlation between
students’ grammar mastery and students’ writing ability on descriptive text. It is
proved by the rxy (0.865) is greater than r table in the degree of 5% significance
(0.301). It is considered that alternative hypothesis was accepted and null
hypothesis was rejected. In conclusion, there was a significant correlation between
students’ grammar mastery and students’ writing ability on descriptive text. In
line with this result, the students’ who have a good grammar, they will also have a
good writing ability.