The Lower Cretaceous Pietraroia Plattenkalk (Benevento Province, southern Italy) has been known since the eighteenth century for its beautifully preserved fossil fishes. During Albian time (about 113Myr ago), deposition of fine marly limestone in a shallow lagoonal environment, affected by cyclic periods of low oxygen levels, led to exceptional preservation of soft tissue in a juvenile theropod. The specimen, diagnosed here as Scipionyx samniticus gen. et sp. nov., is the first dinosaur ever to be found in Italy. The fossil has been mentioned previously in two brief notes, and generally examined in a doctoral thesis. Here we report the full preparation of the specimen which shows details of soft anatomy never seen previously in any dinosaur. The preservation is better than in other lagerstätten (conservative deposits) where theropod soft tissue has been reported, such as the Santana Formation of Brazil and the Yixian Formation of China. Despite this, there is no evidence of feathers or any other integumentary remnants in the Italian specimen. Scipionyx represents a new maniraptoriform theropod. Its discovery is remarkable considering also the scarcity of juvenile theropod dinosaurs in the fossil record.