Six floks, each numbering 11 hens and 1 rooster, of Rhode Island Red strain, at the age of 54 weeks were divided into three groups, and fed on diets containing different amounts of ochratoxin A. The control group (I) was fed a standard mixture without ochratoxin A, groups II and III were given the same diet, with 2.1 and 4.1 ppm of ochratoxin A, respectively, introduced with moulded wheat. The daily feed intake decreased as the ochratoxin A content increased and was 156, 135 and 105 g/day, respectively. The toxin negatively affected the quality of the eggs, especially thickness and crushing strength of the shell. Deterioration of egg-shell quality led to greater loss of egg weight during incubation and lower hatchability. As the ochratoxin A content in the feed increased, the percentage of hatched eggs decreased and survival time of embryos dying during incubation declined. The mass of embryos weighted on 6 and 8 day of incubation and the hatched chicks were lower in experimental than in control group. Ochratoxin A was found in the eggs and also in the blood serum, liver and kidneys of hens, roosters and one-day-old chicks.