The light microscopic examinations of sperm samples from a sterile Fleckvieh-bull stained by the AT specific fluorochrome Hoechst 33258 showed beneath the constantly occurring paraxial tail numerous other malformations, which appeared under the electron microscope as multiple defects of essential cell organelles: defects of the acrosome as irregular thickening or forming of overturned folds "knobbed acrosome", sometimes with vesicles and inclusions inside, partial separation of the acrosome lamina from the nucleus. The defects of the nucleus were present as double-headed sperms, macro- and microcephalic forms besides bizarre shaped heads with gigantic cavities, often filled with membranes, cytoplasm and canaliculi even as heads with ridges which extended from the base to the apex. The main tail defect was a paraxial inserted tail, sometimes coiled, folded or bent down and combined with duplication or even multiplication of the tail with one or two implantation fossae. This multiplication was followed by extensive disturbances of the tail elements as lack or excessive numbers up to the isolation of tubules, fibers and mitochondria. Often there was no contact between tail and implantation fossa. Another defect was the existence of voluminous cytoplasmic droplets covering not only great parts of the tail but also the total head which included "arch like double membranes" and up to 15 tail segments. The persisting cytoplasmic droplet even as the generally occurring paraxial inserted tail are discussed in connexion with the existing hormonal imbalance as probably genetic damage leading to extensive defects during spermiogenesis.