Design considerations are given for a sinusoidal pressure generator (SPG capable of providing sinusoidal pressures up to 26 atmos peak to peak, proportional to input voltage to within 5% over the frequency range from 0 to 10 000 cps. The pressure is generated in a fluid contained in a relatively rigid metal enclosure, by means of a stack of 24 disks of a piezoelectric ceramic, connected electrically in parallel, and arranged so that their displacements add. Several applications of the SPG are discussed including several types of evaluation tests for pressure gauges, evaluation of electromechanical drivers, tests of piezoelectric materials near zero frequency, and study of frequency-dependent effects in liquids. Preliminary relaxation data are shown for two associated liquids, diphenyl metachloride (Aroclor No. 1260) and glycerol.