the circadian expression of the mammalian clock genes is based on transcriptional feedback loops two basic helix loop helix bhlh pas for period arnt sim domain containing transcriptional activators clock and bmal1 are known to regulate gene expression by interacting with a promoter element termed the e box cacgtg the non canonical e boxes or e box like sequences have also been reported to be necessary for circadian oscillation we report a new cis element required for cell autonomous circadian transcription of clock genes this new element consists of a canonical e box or a non canonical e box and an e box like sequence in tandem with the latter with a short interval 6 base pairs between them we demonstrate that both e box or e box like sequences are needed to generate cell autonomous oscillation we also verify that the spacing nucleotides with constant length between these 2 e elements are crucial for robust oscillation furthermore by in silico analysis we conclude that several clock and clock controlled genes possess a direct repeat of the e box like elements in their promoter region we propose a novel possible mechanism regulated by double e box like elements not to a single e box for circadian transcriptional oscillation the direct repeat of the e box like elements identified in this study is the minimal required element for the generation of cell autonomous transcriptional oscillation of clock and clock controlled genes.