ix, 70p.:ill.Using students from two Libyan private schools of English as the source of information, this study focused on grammatical errors committed by some Libyan students of English, which in the view of this dissertation have not received the attention that they deserve as far as grammar teaching and research are concerned. The data for this research were collected from one main source, namely, written scripts of students. The research then employed the descriptive survey design by making a careful observation 0 f the population, bounded by the research parameter. These were then studied and analysed. The research revealed that some Libyan students have serious grammatical problems and the grammatical errors committed by them are varied and many. The analysis also showed that mother tongue interference was a contributory factor to many errors. This study has brought to light the need I to improve the pedagogic strategies in order to help students to improve upon their use of English.