Abstract: A synchronizing circuit for use with a digital communication system is disclosed. A serial data stream is arranged in frames composed of at least two data words containing a synchronization signalling code and binary coded information, respectively. For detecting the alignment of consecutive frames the synchronizing circuit includes a serial/parallel converter and a synchronizing detector logic network for generating two control signals indicating the presence of the synchronization code in form of a normal synchronizing bit pattern or an inverted synchronizing bit pattern respectively. An AND-gate logically links the first control signal delayed by one pulse frame to the undelayed second control signal and generates a synchronizing signal. A time slot generator produces enabling signals by means of counting subsequent system clock pulses under control of this synchronizing signal such that during receiving of different data words of a frame a respective one of the enabling signals is present.