A variety of primary measurement techniques is now available for the measurement of pressure to 1 MPa and above. To ascertain the systematic uncertainty, if any, which exists in the measured pressure using the individual techniques, it is best to perform direct intercomparisons of primary instruments, However, when direct intercomparison is not possible, the next best alternative is to use a highly stable, reproducible transfer artifact such as a simple piston gauge. Such intercomparisons are described here, utilizing a piston gauge calibrated by a mercury manometer (with 0.1 MPa full-scale pressure), four large diameter 'dimensional' piston gauges from two different manufacturen (all with 1 MPa fullscale pressure), and a controlled clearance piston gauge (with 7 MPa full-scale pressure). The area ratio derived from dimensional measuremenk on two of the large diameter gauges, when compared with the ratio obtained from measuremenk traceable to a manometer, agrees within 1 part per million (ppm). For one of the large diameter piston gauges, t h e area value obtained from the manometer agrees within 3 ppm with its dimensional area, and within 10 ppm with the value obtained by its direct calibration against the controlled clearance piston gauge.