This research paper examined the relationship between grammar competence and writing performance among first year students studying in the second semester at Ibn Tofail University in Kenitra in Morocco. The main concern of this study is to investigate whether there is a correlation between grammar proficiency and writing. The researcher used two tests as instruments for the purpose of verifying the correlation between the two variables; one test was in grammar and the other was in writing. The participants were 37 male and female students at Ibn Tofail University who were chosen on the basis that they are in the same level of English language proficiency. They constituted an intact group. The results of the study indicated that there is a significant relationship between grammar and writing. It is also found that there is 14.7% of relationship between the two variables. These findings help university students to improve their writing skills and also assist teachers of English as a Foreign Language (EFL) to design their courses, choose their teaching materials, and teach and assess writing and grammar.