A concept of role is significant to design and implement a secure information system. A role concept shows a job function in an enterprise. A role-based access control (RBAC) model is used to make a system secure. In addition to keeping systems secure, objects have to be consistent in presence of multiple transactions. Traditional locking protocols and timestamp ordering schedulers are based on principles "first-comer-winner" and "timestamp order' to make multiple conflicting transactions serializable, respectively. In this paper, we discuss concurrency control algorisms based on the significancy of roles assigned to transactions. We first define a significantly dominant relation on roles. We discuss a role ordering (RO) scheduler so that multiple con- flicting transactions are serializable in a significant dominant relation of roles. We evaluate the RO scheduler compared with the two-phase locking (2PL) protocol.