The criteria for brittle fracture of a sharp V-notch when it is loaded with antiplane concentrated forces have been considered: a criterion for the maximum average stress, a criterion for the average energy density of deformation, and an approach based on the joint use of the force and energy criteria. Failure loads estimates on the basis of the exact solutions and using asymptotics of stresses near the V-notch tip were found. A comparative analysis of the failure loads obtained through those criteria was carried out. For the asymmetric loading, the initial angle of the crack propagation from the V-notch tip was determined. In the calculation of this angle, the application of the stress asymptotics was shown to result in significant errors and to require the consideration of regular terms in the stress representations.