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The applicability of the chevron-notch (CN) three-point bend test fordetermining the fracture toughness (KIc) of borosilicate glass was studied. As-receivedspecimens with straight sharp notch were also tested in three-point bending for comparisonpurposes. It was found that both chevron and straight notched specimen geometries wereequally suitable for the fracture toughness determination in terms of average values anddata variability according to Weibull and Student’s t statistics. Testing with CN geometryshowed that annealing of specimens at a temperature (550oC) higher than the glasstransformation temperature led to a lower value of KIc. The difference in mean fracturetoughness values (0.75 and 0.64 MPam1/2 before and after annealing, respectively), wasascribed to the different level of compressive residual stresses in the samples.