Rheological properties of thermosetting glass fiber‐filled Dough Molding Compounds (DMC) are useful in understanding the fiber orientation in moldings caused by flow patterns in the mold as well as in assessing the moldability of the material. A rheometer utilizing the squeeze flow between two parallel circular discs was shown to be successful in characterizing the viscous properties of DMC. The viscometric data indicate that addition of glass fibers makes the DMC slurry more viscous and shear thinning and that the extent of these effects increases with the weight fraction of glass fibers. The length‐to‐diameter ratio of the fibers was found to be an important variable. At the same volume fraction, glass fibers with a larger length‐to‐diameter ratio make the DMC more viscous and shear thinning.