Nosema bombycis (Naegeli, 1857) is the causative agent of the "Pebrine disease" in silkworms. N. bombycis spores were found in silkworm samples originating from the Hatay, Bursa and Bilecik provinces. Clinical signs were observed in the infected silkworm larvae. Because of the transovarial transmission risk, all the infected silkworm colonies were destroyed.