This study aimed at identifying the difficulties encountered by Sudanese basic level school students who study English as a foreign Language [EFL] face in when they are writing English sentences. Also, The purpose of the study is to find out which of the two sexes can write sentences better( girls or boys) and the exact level of the pupils. It also explores students' strategies used in learning compound sentence writing. In addition, it aims at finding out the role of sentence writing in improving students writing of compositions and essays in general. The researcher used the descriptive analytical approach to investigate this issue. The method used to collect data was two questionnaires: One for the 8th level (translated in Arabic) students at Khartoum locality and the other for teachers of English language, for the academic year (2016). A program using SPSS was applied in the statistical analysis of these two questionnaires. Besides a Cronbach alpha formula was tested and a part of compound sentence writing was added to check the validity and reliability of these two instruments. The statistical results and a sentence writing part reveal that students are weak in writing sentences. The use of old methods in teaching and untrained teachers played role in their weakness but there are some other obstacles, which hinder the writing process. Based on these difficulties, old methods of teaching writing should not be used, teachers should be trained and students are in need of motivated methods in writing compound sentences