Circular RNAs(circRNAs)are involved in various biological processes and disease pathogenesis.However,only a small number of functional circRNAs have been identified among hundreds of thousands of circRNA species,partly because most current methods are based on cir-cular junction counts and overlook the fact that a circRNA is formed from the host gene by back-splicing(BS).To distinguish the expression difference originating from BS or the host gene,we pre-sent differentially expressed back-splicing(DEBKS),a software program to streamline the discov-ery of differential BS events between two rRNA-depleted RNA sequencing(RNA-seq)sample groups.By applying to real and simulated data and employing RT-qPCR for validation,we demon-strate that DEBKS is efficient and accurate in detecting circRNAs with differential BS events between paired and unpaired sample groups.