This investigation shows that below a certain value of the maximum pressure in the region of contact, fatigue cracks are not initiated. This critical value of the maximum pressure is lower the greater the area of contact. In alpha brass the rate of crack initiation increases with increasing values of the maximum pressure, whereas in the Al-Mg-Zn alloy the rate of crack initiation decreases as the maximum pressure increases.Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference held in Chicago, Illinois, October 17–19, 1967.