Chicken infectious anaemia is a viral disease in young chickens which characterized by aplastic anaemia and immunosuppression. Between January 2004 and July 2005, an unusual hemorrhage in subcutaneous and intramuscular tissues of broiler chickens at slaughter houses of Mashhad, Isfahan and Tehran provinces were occurred. Postmortem examination revealed severe hemorrhages in the wings and muscles of the legs and atrophy of the thymus in all the affected chicks. Twenty two flocks, collected from slaughter houses of these provinces investigated in this study. PCR was carried out for detection of DNA virus in pooled liver and thymus suspensions and blood samples were collected for ELISA assay. All of the collected tissue samples from the affected flocks were found to be positive. Totally 440 serum samples collected from the affected flocks were tested in which 316 (71.8%) of the sera were seropositive with seroprevalence ranging from 25% to 100%. The number of PCR positive samples was significantly higher than seropositive samples measured by ELISA. In conclusion, it seems that CIAV has a widespread distribution among the Iranian broiler flocks and the virus plays a critical role in development of hemorrhage in broiler chickens at the slaughter houses.