The paper presents the results of tests on fatigue crack growth under bending in an elastic-plastic material. Specimens with rectangular sections and stress concentrator in the form of external one-sided sharp notch were used. The tests were performed under the stress ratios R = - I, - 0.5, O. The test results were described by the /'i ]-integral range and compared with the /'i K stress intensity factor range. It has been found that there is a good agreement between the test results and the empirical formula of fatigue crack growth rate, which includes the /'i ]-integral range.