peer reviewed ; After ingestion of moulded beet pulp silage, cases of cerebro-cortical necrosis (CCN) and mortalities were observed in a dual purpose Belgian Blue (BB) herd. Contamination with Paecilomyces spp., a mould that produces byssochlamic acid, malformins and patulin, was proven. Twenty-five days after progressive introduction of beet pulp silage into the ration, most of the animals showed diminished appetite, excessive salivation and decreased milk production. Some of them showed anorexia, head pressing and blindness while 4 animals died within 1 week after onset of neurological symptoms. The survivors had been treated successfully with thiamine and recovered completely within five days. Once the beet pulp silage had been identified as causative agent, it was removed from the animals’ ration and no more clinical cases were observed. Silage was obviously moulded and analysis revealed the presence of 1.6 million CFU Paecilomyces spp./g of silage. Although no further investigation was undertaken to identify the mycotoxins, intoxication with patulin was suspected, since other mycotoxins produced by these species are less toxic. Although it has not been described that CCN can be induced by ingestion of Paecilomyces spp., it seems that there is a close relation between ingestion of Paecilomyces-contaminated silage and clinical signs observed in this herd.