English Skills Courses are important requirements for the attainment of a degree at the University of Eastern Africa, Baraton. This study was set to establish the impact of these English Skills Courses on the written syntactic construction by university students. Focus was on syntactic errors because such errors mar the intended meaning of the sentence, paragraph or essay. The assumption of this study was that English Skills Courses help the students to lessen syntactic errors in their written work and that syntactic errors are the most recurrent errors made by the students. The theoretical framework employed in this study was based on the input hypothesis, the error analysis, and the inter-language theory. A purposive sampling method was used to select a target group of 15 students and a control group of 15 students. The methods used were tests and observation schedules. Essays written for placement tests, mid-quarter exams, continuous assessment tests and final exams were collected and analysed for syntactic errors. The analysis included checking how frequent the errors occur and the trend they take after instruction.