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An elastic-plastic analysis was used to accuratel~¢ measure the microscopic cleavage strength o~of notched bars of high nitrogen steel in bending. It was found that o~f increases as the root radius of the notch/9 decreases. For/9 > 0.010", the variation of o~f with p, and the difference between 0~f and the cleavage fracture strength of a plane tensile specimen, of, may result from a statistical effect, due to differences in the volume of highly stressed material in the plastic zone• For/9 < .010", the primary reason for the apparent increase in o~f with decreasing p, is the steep stress gradient at the notch tip, which forces the critical plastic zone size to extend further to insure that unstable microcrack propagation can occur. Both the statistical and stress gradient effects have been quantitatively evaluated and found to be in good agreement with the experimental data.