Writing is secondary media of communication, because through writing people can do the communication too. Writing is important, because communication not only spoken language, but also written language. Although writing is important, many students who learn English assumption that writing is difficult skill. It happens because of many factors such as grammar and spelling problems. It may also caused by differences between their Indonesian language as the first language and English as the foreign language. Write in Indonesian language is easily causes they are familiar with vocabulary and grammar. This is different when they write in English. There are many students’ problems and the causes in writing. Therefore, this research was conducted in order to find out the students’ difficulties and the causes in writing descriptive text at the X-Science 1 Class of Sekolah Menengah Atas Negeri 01 Kotabumi. This research employed case study as the research designed with qualitative approach. The subject of the research was 33 students. The instrument used to collect the data were documentation and field note. Based on the data analysis, it found that, there were eight problems causes students’ difficulties in writing namely grammar, sentence structure, word choice, punctuation, capitalization, spelling, content and organization. There also found seven causes of students’ difficulties in writing namely the nature of writing process, lack learner motivation, inadequate of time, lack of practice, lack of teacher feedback, lack of vocabulary and lack of developing ideas.