Virus-like particles found in the epidermis of carps affected with “carp-pox” are described. In the nuclei of the host-cells round to ovoid particles, surrounded by a single-layered membrane with a diameter of appr. 110 mμ are observed. In the cytoplasm the virus-like particles have a doublelayered membrane and a diameter of about 140 mμ. In both nucleus and cytoplasm, forms of the virus occur differing withs respect to their nucleoids. It is suggested, that the virus-like particles represent a virus belonging to the Herpes-group.