The main clinical signs of the disease in Penaeus monodon were the white spots on the exoskeleton (Fig. 1). The white spots were particularly obvious on carapaces removed from diseasedshrimp, and were readily observed even on carapaces from lightly infected specimens. Histopathological study demonstrated that the epidermis of the diseased shrimp was attacked by a viral agent as was evidenced by the presence in this tissue of degenerated cells characterized by hypertrophied nuclei with inclusions (Fig. 2).