This article presents data on and discusses the application of statistical process control (SPC) to rheological measurements. With the help of case studies on capillary rheometry and dynamic oscillation, it is shown how SPC, coupled with careful calibration and maintenance of rheometers, can demonstrate significant improvement in the accuracy and precision of rheological measurements. This improvement is evident on examination of the various control charts discussed and the narrowing of their control limits. Specifically, individual and moving range control charts for the apparent viscosity measured at an apparent shear rate of 100 s(-1) using capillary rheometers are discussed. For the dynamic oscillatory rheometer, the charts presented are for the magnitude of the complex viscosity measured at a frequency of 1 Hz. This article shows how SPC provides quality assurance by assuring that erroneous data will not be inadvertently reported. The issues discussed are of universal interest and relevance, not only to rheologists, but to all scientists and engineers who make and/or use measurements.