Abstract: Cellulose is a major structural component of the plant cell wall. Thus, understanding cellulose biosynthesis is important in plant biology and biomass production. In this study, we analyzed the phylogenetics of Arabidopsis cellulose synthesis genes (AtCESA) and their expression using the microarray data from NCBI. Furthermore, we analyzed the expression of 10 AtCESA promoter:GUS reporter genes in different vegetative and reproductive growth stages of Arabidopsis. Our results showed that AtCESA1, -3, and -6 or -6-like protein genes were probably required for primary cell-wall complexes, whereas AtCESA4, -7, and -8 protein genes were possibly involved in secondary cell-wall complexes. AtCESA1, -3, and -6 show high global expression in all tissues, whereas AtCESA4, -7, -8 are highly expressed in root, stem and leaf vein. We found 3 segmental duplication genes (AtCESA5/6, AtCESA2/9 and AtCESA1/10); AtCESA5 may be partially redundant with AtCESA6. In addition, AtCESA9 showed tissue-specific expression in meristems and flowers and may be partially redundant with AtCESA2. AtCESA genes may be important for primary and secondary cell-wall formation during different developmental stages in Arabidopsis and in different organs.