An outbreak of zearalenone mycotoxicosis occurred between early March and mid-April involving 62 suckling piglets of both sexes. The clinical picture was characterized by edematous swelling and reddening of the vulva, sometimes associated with reddening and/or necrosis of the tail. Six female piglets had congenital lesions of the external genitalia while in the remainder clinical signs appeared 2 to 3 d after birth. No sows ingesting the contaminated feed had signs of hyperestrogenism. The distribution of affected litters showed a correlation with poor hygienical conditions. Zearalenone residues were detected only in feed samples from mangers where the hyperestrogenic syndrome occurred.