Chicken infectious anemia (CIA) is widespread viral disease in countries with the intensive poultry industry. In susceptible birds CIAV causes anemia subcutaneous and intramuscular hemorrhages, lymphoid tissue atrophy immunosuppression, cachexia and increased mortality. Protection of progeny relies not only on age resistance but also on maternally delivered antibodies (Mabs) so possessing the information on level and persistence of Mabs is of great significance. In our study experimental infection with CIAV was performed on one and seven days old broiler chickens from naturally infected parent flock during the rearing period. In infected birds, clinical signs hematological findings and humoral immune response were examined. After euthanasia, we looked for specific pathomorphological and histopathological changes that indicate the presence of CIAV infection. In all one and seven days old chickens maternally derived antibodies were established. No clinical signs of CIA were observed, hematological findings showed no deviation from referent values, and there were no specific pathomorphological and histopathological changes at postmortem examination. According to previous knowledge, only serological negative flock if infected in time of laying represent risk for vertical transmission to progeny where typical disease with mortality will appear. The absence of Mabs in one day old chickens is critical point in break of disease. Typical clinical picture in day old chickens rises only when vertical transmission occurs.