A case‐study method is proposed to determine service loading from fracture surface striations. Although it is well known that striation spacing relates to the crack growth rate, it is considered impossible to determine maximum and minimum loads under service loading conditions, and which define the stress ratio R, from an analysis of the striation spacing. This paper presents a new method of determining the maximum and minimum loads which is based on the experimental fact that the relative height of a striation H to striation spacing s is strongly influenced by the stress ratio. The results of fatigue tests on 2017‐T4 A1 alloy showed a definite correlation between these parameters. The difficulty of measuring striation height was overcome by taking the measurements in a scanning electron microscope after sectioning the specimens at a large inclined angle. Striations under a stress ratio R=−1 are compressed and flat, and the ratio H/s is small. With increasing R, the value of H/s becomes large. Therefore a standard laboratory test that determines the relationship between s and ΔK, and also between H/s and R enables one to estimate service loadings from fatigue fracture surfaces. Copyright © 1991, Wiley Blackwell. All rights reserved