A test machine has been designed and constructed to measure fretting corrosion quantitatively under precisely defined conditions. Damage is measured by weight loss of two 1-in. diameter cylindrical specimens, one of which is subject to radial oscillatory motion. Specimen load is applied pneumatically to a maximum pressure of 27,000 psi. Frequency of motion can be varied between 56 and 3000 cpm. Relative slip is established by means of an adjustable cam to values between 0.000 and 0.008 in. and is measured using either a comparator microscope or a strain gage transducer. A stainless steel cell surrounds the specimens permitting control of environment. Using SAE 1018 steel against itself, it was found that rate of fretting corrosion decreased gradually during a brief run-in period, after which it became constant. Weight loss was found proportional to total relative slip. Increase of applied load on specimens first increased fretting corrosion, reached a maximum, then decreased. Corresponding slip became less at high loads as imparted motion was lost elastically in various components of the machine. This corresponds to the situation observed by others for which fretting damage approaches zero when relative slip is zero. Further measurements are in progress.