1. The effect of feeding trichothecene-contaminated diets with graded concentrations of deoxynivalenol ranging from 120 to 4900 micrograms/kg to groups of laying hens was investigated. 2. Food intake, weight gain and egg production were not affected by mycotoxin administration. No significant differences were found between groups. 3. The overall results from the hatching tests did not reveal any significant differences in fertility, hatchability or perinatal mortality, which could be explained by the mycotoxin content in the diets. 4. Body weight at hatching and viability of the chicks were not affected by the mycotoxin concentrations in the diets. 5. The incidence of chick developmental anomalies was increased in the mycotoxin-administered groups compared to controls. Minor malformations were the dominating anomalies and included unwithdrawn yolk sac and delayed ossification. The most frequent major malformations were cloacal atresia and cardiac anomalies.