Numerous coccidian stages were found in the kidney tubules of the golden carp (Carassius auratus gibelio). The merogonial and gamogonial stages were localized extracytoplasmally in the microvillous region of the epithelial cells. The host-parasite interface consisted of i) a large area where the parasite was separated from the host cytoplasm by the parasitophorous vacuole membrane only, and ii) a zone of multiple fusions of the host cell membrane investing the parasite to the neighbouring microvilli. The taxonomic status of the extracytoplasmic stages is not clear, however, their possible appurtenance to Eimeria scardimi, which was frequently found in the kidneys of golden carps in the same population, is discussed.