|The topic dealt with error analysis in language use while communicating or in written and the way it affects composition writing among pupils in selected schools in Chepkube zone in Mt. Elgon District .This errors involved language flow, its structure or form and influence of first language from mother tongue. As the saying has it that a mistake is never considered a mistake unless it is repeated. Most learners in this region do not acquire high marks in composition writing and end up receiving below average marks. This happens because majority of them do not follow required rules governing language use. The root cause emanated from the influence of the mother tongue that had its own form and hence affected the second language in spoken and structure. This trend of making errors in composition writing in their respective schools, during their mock examinations and latter in their final KCPE examination nationally need to get a lasting solution so that learners can obtain better results. Past research shows that L1 influences the learning of L2. The source of this research therefore involved learners who wrote composition, had dialogue and attempted given exercises in their respective schools .The research was guided by the hypothesis that errors in language use affects its flow, structure and speech. This data was guided by error analysis theory. The theory was useful in its collection, error classification and error explanation. Once collected, this data was to be used by researchers basing on errors using quantitative and explanation approach .Its outcome will be of value to learners, teachers, researchers and other writers of Kiswahili books.