This letter proposes a receiver-originated physical-layer secure transmissions scheme (ROST) which consists of two-phase communications. In phase 1, the receiver sends a pseudorandom signal (only known by itself) to the transmitter and in phase 2, the transmitter directly sends out the mixture of its confidential message and the received pseudorandom signal. The receiver could estimate the channel with the help of the pseudorandom signal before cancelling it from the received mixed signal, and finally detect the confidential information. By contrast, the eavesdropper can hardly obtain any confidential information because it cannot estimate the channel without any pilot signal in both phases transmissions and is interfered by the pseudorandom signal. Furthermore, we discuss the secrecy capacity of ROST and show that ROST can always keep the security of the confidential message, achieve much higher secrecy capacity than the traditional scheme, even without any channel information at the transmitter.