We have recorded the magnetic signal generated by the human cardiac muscle with the help of a very sensitive flux-gate sensor. First, we have verified the feasibility of such detection inside a magnetically shielded room, then repeated this same experiment within our laboratory and in a low shielded environment. Results have shown the easy operation of a flux-gate sensor for this purpose and the efficiency of fast numerical processing in a low shielded environment. This leads in both cases to a voltage signal-to-noise ratio of about 5 within a 100 Hz bandwidth, which corresponds to the actual limit of the flux-gate probe.©1998 American Institute of Physics.