Second Language Teaching is intended to enhance students’ communicative abilities in a language other than their mother tongue. In this regard, teaching syntax (as effective sentence writing is the basis for good essay writing) is of an unequaled importance for university students to succeed in their studies. Nonetheless, ESL/EFL students- Rwandan students in this case, face many challenges while writing in English. This study that was conducted in Institut d’Enseignement Supérieur de RUHENGERI (INES-RUHENGERI) has shown that a good number of Rwandan students are not capable of writing good and comprehensible texts. Most of their sentences do not clearly express what they mean. This study highlights types of English syntactic errors made by these students, their causes and ways to overcome them.