An automated optical section method for quantifying the orientation state of short fibers in injection molded parts is presented. The method is based on imaging tracer fibers in index of refraction-matched transparent composites. The experimental methods and performance characteristics of the method are described. The method is non-destructive, operator-independent, economical and rapid. Scanning to depths of about 1.3 mm without cutting is possible at 10 μm spatial resolution at processing rates of < 10 min mm −3. Straightforward modifications should allow processing rates >1 mm 3 min −1. Calibration tests suggest that fiber orientation is quantified to within the accuracy expected based on the degree of solid angle discretization chosen for analysis (5 ° here). Reproducible fiber orientation distributions are realized for sample domain sizes of about 2 mm × 2 mm × 0.15 mm. The orientation distribution function is quantified as well as the orientation tensor components. Convenient graphical visualizations of the 3D orientation distribution function and tensor representations are provided.