The details of the construction and calibration of high frequency magnetic probes, used to measure the transient magnetic fields in a linear pinch device, are described. A simple and reliable calibration technique, using conventional laboratory electronic equipment, was developed to measure the absolute sensitivity of magnetic probes in the frequency range of 1–50 Mc. Factors affecting the frequency response of magnetic probes are considered, and high frequency design and construction are discussed. A double probe, which measures two magnetic field components simultaneously is described. The use of these probes is briefly mentioned.