This paper presents a compilation of available fatigue-test data on piping components and derives therefrom stress-intensification factors relative to straight pipe. These factors are strictly applicable only to the limited range of sizes for which fatigue tests were made. In view of the importance of proper consideration of stress intensifications in cyclically stressed piping and the lack of theoretical developments which would serve to evaluate their magnitude for all shapes involved, the author has taken it upon himself to suggest empirical correlations by which the application of the available data can be expanded to a wider range of sizes and conditions.