Silesaurus measured approximately 2.3 meters long, and was facultatively bipedal. It was light and built for speed.
Silesaurus was an herbivore. The teeth were small, conical, and serrated. The tip of the dentary has no teeth, and some paleontologists think that it may have been covered by a beak.
Most scientists think that Silesaurus was not a dinosaur, but rather a dinosauriform. Dinosaurian features lacking in Silesaurus include an enlarged deltopectoral crest (a muscle attachment on the humerus), and epipophyses (enlarged tendon attachment above the postzygapophysis) on the cervical vertebrae.