A bluetooth hands-free car kit includes a hands-free cell phone/PDA holder electrically connected to the internal electric circuit of a car for receiving and amplifying sound, a bluetooth adapter insertable into the hands-free cell phone/PDA holder for wireless communication with a cell phone/PDA through a bluetooth communication technique, and an audio transmitter receiver device insertable into the bluetooth adapter for receiving and transmitting audio signals. The bluetooth adapter has a pivoted clip biased by a spring member for engaging a retaining notch on one lateral side of the audio transmitter receiver device to lock the audio transmitter receiver device to the bluetooth adapter upon insertion of the audio transmitter receiver device into the bluetooth adapter.