This study on the "ANALYSIS OF WRITTEN ERRORS MADE BY FIRST FORM ARTS STUDENTS : THE CASE OF SOME SELECTED SECONDARY SCHOOLS IN BUJUMBURA CITY" tried to find out and solve the problems encountered by both teachers and learners when teaching and learning the writing skill. In this study, I have investigated mainly the written errors from word order, word choice and word formation. After observing many failures in the National Test, I decided to find out what impeded the good understanding of the message transmitted through students' writings by focusing on how students choise the appropriate word, put it in its good place and wrote it accurately. Unfortunately, by evaluating them, I found out that many errors were done in the writing skill. Some of them were found in the parts of their compositions. They respected the three parts of a good composition (introduction, body and conclusion) but they did not respect the constituent elements of each part. There was the lack of linking words and mixture of arguments. In the content they mainly mad emistakes in word order, word choice and word formation. I recongnised, then, that studients could fail only because they did not know how to write what they wanted to transmit as a message to their teachers. All this was done with the intention of finding solutions to problems encountered when teaching / learning the writing skill.