- The objective of this study was to determine the risk of death and potential for prevention of mortality in a large population of children with growth hormone deficiency (GHD). The Canadian GH Advisory Committee registry was initiated in 1967 to include all persons in Canada treated with pituitary-derived GH (1967-1985). Since 1985, the registry has been maintained for continuous surveillance of those treated with biosynthetic GH. Thirty-seven children have died out of a total of 1366 children treated for GHD in the 25 years up to December 31, 1992. Individual cases were reviewed for circumstances before death and autopsy information. The likelihood of individual deaths being caused by potentially preventable endocrine causes was graded on a scale of 1-5. Survival curves were analyzed for the children with idiopathic GHD and craniopharyngioma. Age- and sex-specific mortality rates for children with idiopathic GHD were compared with those of the general population. The overall crude mortality rate was 2.7%. The most frequent cause of mortality was tumor recurrence (11/37). A surprisingly high proportion of deaths (9/37) were caused by the preventable endocrine complications of adrenal crisis and hypoglycemia. Children with idiopathic GHD receiving GH therapy had similar age- and sex-specific mortality rates compared with general population rates, except in a high-risk subgroup of males diagnosed with GHD before 2 yr of age. The highest mortality occurred in children with GHD secondary to craniopharyngioma. We concluded that preventable sudden deaths caused by adrenal crisis continue to occur in children with hypopituitarism. A high level of vigilance must be maintained in this population.