A study of bovine mortality involving a stratified random sample of farms and veterinary practices was carried out in Northern Ireland during 1992. In the farm survey over 3500 deaths were reported from 1069 farms and 237 farms reported no deaths. The estimated total number of deaths of cattle up to two years old was 12,332, a figure which excludes an estimated 7921 stillbirths. The estimated annual mortality rates for six- to 24-month-old cattle, one- to five-month-old calves and neonatal calves were 0.79 per cent, 0.82 per cent and 1P02 per cent respectively. The stillbirth rate was 1.86 per cent. Respiratory syndromes were associated with 37 per cent of the deaths of six- to 24-month-old cattle and gastrointestinal syndromes were associated with 22 per cent; in one- to five-month-old calves these syndromes were associated with 37 and 33 per cent of the deaths, respectively. Stillbirths accounted for 62 per cent of all the deaths of calves under one month old, and the neonatal disease complex accounted for 39 per cent of the deaths of calves which were born alive but died within one month of birth.