The fracture properties of molded articles containing weld-lines are analyzed by a fracture mechanics approach, treating the weld-line as a sharp crack. The theoretical length of the weld-line crack is estimated from diffusion properties and a simple model of cooling in a mold. These estimated weld-line crack lengths are found to be in excellent agreement with weld-line crack lengths calculated from measured fracture properties. Above a critical melt temperature, this weld-line crack length will fall below a critical crack length, whereby the weld-line will no longer initiate brittle fracture. This critical crack length is a function af lie material’s inherent yield strength and fracture toughness. The embrittling effect of weld-lines can also be easily removed by surface treatments such as surface milling or solvent polishing. Weld-lines are, therefore, determined to be near-surface flaws, which embrittle notch sensitive materials such as most amorphous polymers.