Ten-day-old cockerels were infected with N. asteroides or N. transvalensis by the oral or intraperitoneal routes. Clinical signs included depression, gasping and emaciation. Grey nodules or foci were observed in the lungs, air sacs, liver and breast muscles. These organs showed necrosis, granulomas, lymphoid follicles and infiltration of lymphocytes, heterophils and macrophages. Intraperitoneal infection resulted in a more severe disease with either organism. N. transvalensis appeared more pathogenic than N. asteroides intraperitoneally and vice versa with the oral route.