The development of an indirect immunoperoxidase test for turkey rhinotracheitis (TRT) serodiagnosis is described utilising CER-monolayers. There was no nonspecific binding of Newcastle or influenza antibodies to TRT virus infected plates. Field sera from vaccinated and nonvaccinated turkeys of different ages have been tested. Immunoperoxidase test showed higher sensitivity than serum neutralisation test. The specific bar-like cytoplasmic staining has been demonstrated with positive sera proving the specificity of staining. Nonspecific peroxidase background staining was excluded through preincubation of tested sera on noninfected monolayers. Glycerol preserved plates could be kept as long as 6 months at 4-8°C, and shortened the test time to 2-3 hours.