Contaminants in the lubricant of rolling bearings have a strong life-reducing effect. Various experimental processes of investigating into these influences on the life are discussed in detail. A method is presented by means of which the effect of cycled foreign particles on the fatigue life and the underlying physical correlations can be analysed largely free of unwanted interfering parameters. From the results of some thousands of test runs together with detailed analysis of a large number of actual applications an extension of the standardized life calculation for standard rolling bearings is derived taking into account the oil cleanliness according to ISO 4406. For applications where contamination of the lubricant cannot be eliminated, bearings made of the new material AMS 5898 offer an up to ten times longer fatigue life than conventional bearings.