Experimental and modeling studies on tensile fracture behavior of notched unidirectional Si-Ti-C-O (Tyranno fiber) reinforced BMAS (barium magnesium aluminosilicate) glass matrix composite were carried out. The longitudinal crack arose at the tip of the transverse notch before overall fracture. The critical energy release rate around at initiation of the longitudinal cracking was estimated to be nearly 100 J/m(2) by application of the present model to the experimentally observed relation between the stress of the composite in the very early stage of longitudinal cracking and the notch size. The notched strength was higher than that predicted by the fracture mechanical criterion due to the blunting arising from the premature longitudinal cracking, but it was lower than that predicted by the net stress criterion due to the constraint effect arising from the bridging of the fibers and the spalling of the segmented matrix into the longitudinal crack.