The neurotropic disease of pigeons caused by a variant avian paramyxovirus type 1 virus was confirmed in 866 lofts in Great Britain during 1984, in comparison with 192 lofts during July to December 1983. The 1984 outbreaks were spread over 48 counties in England and Wales and three regions in Scotland. The main methods of spread of disease in the 1984 outbreaks appeared to be similar to 1983 with 574 of 866 probably resulting from contact with infected birds at, or travelling to, races or shows. In 791 of 866 (92.5 per cent) outbreaks in 1984 disease was seen only in unvaccinated birds. A further 61 (7 per cent) occurred in inadequately vaccinated birds or birds vaccinated after clinical signs appeared.