Reversed plane bending fatigue tests were conducted on two kinds of structural steels, JIS S35C and SCM435. The behavior of small surface cracks was continuously sampled by replica technique, and their probabilistic properties were investigated. The distributions of fatigue crack initiation life and fracture life were found to be represented by log-normal distributions. The fatigue crack growth rate of S35C in the range of crack length from 0.1 mm to 3 mm is expressed in equation form.