Abstract: A protection circuit for an implanted telemetry circuit used to telemeter ECG or other low level signals sensed on the same lead whereon high level stimulation or other signals may also appear. The protection circuit includes a first FET switch that selectively connects a buffered monitoring point of the lead to the input of the telemetry circuit whenever a telemetry mode of operation is desired. A second FET switch switchably connects the buffered monitoring point to ground in the presence of any high level signals appearing on the lead, thereby preventing such high level signals from being applied to the telemetry circuit.