Three chicken infectious anemia (CIA) virus strains were isolated from 10 different sick broiler and replacement chicken flocks with the MDCC-MSB1 cell line. One-day-old specific-pathogen-free chicks were inoculated later, with the three original samples being positive in tissue culture; one induced signs and lesions, another only lesions typical for CIA. One isolate was selected for further trials and showed resistance to chloroform and heat (75 C for 5 min) and passed through a 45-nm filter membrane but did not pass through the 22-nm filter. These characteristics were similar to the Del Rose reference strain of chicken anemia virus. By electron microscopy, the diameter of particles obtained from the pellet of infected cell cultures was between 22 and 27 nm. Serology survey carried out with 580 serum samples from different poultry farms all over the country with a commercial enzyme-linked immunosorbent assay kit gave proof of widespread seroconversion, indicating that CIA should be considered endemic to Mexico.