Abstract For a better understanding and evaluation of shock absorber performance, detailed data upon their relevant physical parameters, such as spring characteristics and energy dissipation properties, have been measured in a test jig. Down hole tests where well defined sinusoidal vibrations are generated in a 1000 m vertical drill string by means of a down hole exciter were also performed. The drill string response above the shock absorber is measured by a hard wired MWD tool giving high frequency data on accelerations, WOB, torque and pressures. Examples of test results for different types of absorbers are presented and discussed for both laboratory and downhole tests.