In this study, nylon tubes were welded to nylon plaques using laser transmission welding. A conical mirror inserted inside the tube was used to guide the laser beam along the weld path around the inner circumference of the tube. The effect of beam location with respect to the tip of conical mirror on beam distortion was modeled and assessed experimentally. The effects of the laser power, the angular speed, and the number of passes on the joint shear strength were examined. Process parameters that gave good joint strengths were identified.