['Clinical cases of hemangioma associated with subgroup J avian leukosis virus (ALV-J) have been reported in commercial chicken layer flocks since 2006. We attempted to reproduce hemangioma through experimental infection with ALV-J to evaluate viral pathogenicity in layer birds and their progenies.', 'Body weight and indexes for immune organs of chickens infected with ALV-J strain SCDY1 were lower than those in controls. Proliferation of lymphocytes was observed in many tissues, and viral integration was detected in the genome of lymphocytes at 14 days post-infection, along with virus shedding. ALV-J was also efficiently transmitted from eggs to progenies. Embryo hatchability and progeny mortality were lower than those for controls. The efficiencies of virus shedding and virus integration in the lymphocytes of progenies were higher than those in parents.'] Is reproduction of hemangioma by infection with subgroup J avian leukosis virus : the vertical transmission more hazardous than the horizontal way?