Defects in temporary pacemaker electrode catheters should be considered in the differential diagnosis of inappropriate pacing by ventricular inhibited demand units. In two of three patients, sensing failure was the only manifestation of electrode fracture. Fractures often occur near the junction of the steel pin terminal and electrode and, if intermittent, may be overlooked if flexion maneuvers are omitted from the routine of catheter testing. Unless this complication is appreciated and corrected it may progress to further disruption of the circuit with complete loss of pacing. Defects in temporary pacemaker electrode catheters should be considered in the differential diagnosis of inappropriate pacing by ventricular inhibited demand units. In two of three patients, sensing failure was the only manifestation of electrode fracture. Fractures often occur near the junction of the steel pin terminal and electrode and, if intermittent, may be overlooked if flexion maneuvers are omitted from the routine of catheter testing. Unless this complication is appreciated and corrected it may progress to further disruption of the circuit with complete loss of pacing.