The objective of this research was to improve the students' spiritual intelligence in English writing through Whole Brain Learning strategy. Therefore, this study was conducted as a classroom action research. The research pocedure followed the cyclonic process of planning, action, observation, and reflection. This process was preceeded by pre-liminary study in order to know the students' spiritual intelligence in English writing before being taught by the whole brain learning. The data was collected from the results of spiritual intelligence questionnaire, observation, interview, and documentation. The subjects of the research were 30 students in English Education Department, Universitas Islam Negeri Sumatra Utara. The quantitative data were analysed by using t-test in Statistical Package for the Social Science (SPSS) and the qualitative data were analysed by using Miles and Huberman technique: data reduction, data display, and verification. As a result, there was a significant improvement in students' spritual inteligent in English writing when they were taught through Whole Brain Learning.