We have developed a high temperature superconductor (HTS) dc SQUID gradiometricmeasurement system for routine applications in non-destructive evaluations. Low values ofthe white flux noise and white field gradient noise were measured for gradiometersoperating at 77 K. Low frequency noise was suppressed using an ac bias technique, even ina magnetically unshielded environment. First-order planar dc SQUID flip-chipgradiometers were used in the measurement system for stable operation underelectromagnetically noisy conditions. A synchronous filter was employed to remove allharmonic components of parasitic line frequency interference. This improved theresolution of the system in a typical laboratory or industrial environment showingstrong magnetic gradients of the line frequency signal due to nearby metallicconstructions. Test scans of contaminations with magnetic particles were performed.