Three chicken infectious anaemia virus (CIAV) isolates were obtained from broiler flocks with anaemia and poor performance, and were designated AIP-1, 2 and 3. All isolates were resistant to treatment with chloroform and were able to pass through 50-nm pore-size filters. The CIAV isolates induced signs and lesions of chicken infectious anaemia (CIA): thymus atrophy, bone marrow aplasia, low haematocrit values, and body weight reduction when inoculated into 1-day-old susceptible chicks. Microscopic lesions were a reflection of macroscopic observations. CIAV-specific antigens have been demonstrated in tissues of experimentally-infected chicks using monoclonal antibodies specific for CIAV. The presence of antibodies against CIAV in breeders was determined by indirect immunofluorescence tests. Although the chicks derived from breeder flocks that possessed antibodies against CIAV, they were not refractory to infection. These findings, the characteristics of the virus and the virus-induced lesions, demonstrate that CIAV is present in Argentina.