The life-margin of oscillating caged needle roller bearings is determined in an explicit non-statistical manner. Life-margin is the difference between the first macroscopic evidence of spalling fatigue and the end of useful bearing life. The bearings were life tested under service conditions closely duplicating those in helicopter rotor vertical and horizontal hinge pin locations. Test results are presented for nineteen bearings lubricated with MIL-L-7808 oil. The use of magnetic chip-detectors and spectrometric oil analysis as failure indicating devices are discussed.Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE Lubrication Conference hold in Atlantic City, New Jersey, October 8–10. 1968.