Strength of a glued joint with a crack-like defect in the glued interlayer is under consideration. The strength of three-layer specimens depending on their geometrical dimensions (thickness and length) is estimated in full-scale experiments. In analytical modeling, the glued joint is considered as structured three-layer composite, the rectilinear crack in which is located parallel to a narrow plane interlayer. For description of the fracture process, the modified Leonov-Panasyuk-Dugdale model is applied. This model makes use of the supplementary parameter such as the plasticity (pre-fracture) zone width of the glued interlayer. Materials with the regular structure exhibiting brittle or quasi-brittle fracture type are considered under conditions of plane strain. Under conditions of tension applied at infinity along the normal to the glued interlayer, the mode I fracture is implemented. The estimates support the appropriateness of applying the modified analytical model for prediction of fracture of glued components.