Deoxynivalenol (DON) and zearalenone (ZON) produced by Fusarium species are agriculturally important mycotoxins of relevance to livestock health. While ZON is known to cause oestrogenic syndromes in animals, a moderate ingestion of DON is associated with reduced performance and immune function. Among farm animals, ruminants appear to have a higher tolerance towards the effects of DON and ZON. As a consequence, feed producers may allocate cereals and roughages which appear contaminated with Fusarium toxins to ruminants. In combination with enhanced toxin concentrations during so-called Fusarium years, the possible effects in ruminants cannot be overlooked. However, only limited and inconsistent literature data are available about the effects of DON and ZON on ruminants. On the basis of the literature, the kinetics, biotransformation and carry over, as well as the effects of DON and ZON on ruminants, are reviewed. Furthermore, dosage and duration of toxin exposure as well as genetic and physiological factors of ruminants which could influence the variability of the toxin effects are considered and discussed. It is concluded that additional research is needed to study the effects of DON and ZON on ruminants, especially in lactating dairy cows.