A low‐noise preamplifier circuit for use with Halltron HR‐66 Hall effect probes in the frequency range dc to 100 kHz, shows a wideband noise of 6‐ and 2‐mG rms for bandwidths of dc to 100 kHz and dc to 100 Hz, respectively. Below 100 Hz the noise is due to the 1/fnoise from the Hall probe, while white preamplifier noise dominates above 100 Hz. Above 1 kHz, preamplifier noise exceeds the noise of the Hall probe alone by a factor of five. dc drift of the system is approximately 10 mG in 24 h.