Nine test broods selected from 3 groups of RIR chickens which four weeks before hatching consumed ochratoxin A contaminated feed at doses 0 (control group), 2 ppm and 4 ppm were examined. During a 63-day observation period egg production in birds receiving 2 ppm of ochratoxin decreased egg production by 78.14% and hatching by 51.25%. In dead embryos, losses of body weight, defective positioning and destruction of parenchymatous organs were found. In the 4 ppm group necrosis of lymphoid cells and eosinophilic of bursa of Fabricius was noted.