The authors studied life expectancy and risk factors for mortality of persons in the vegetative state (VS). The study participants were 1,021 California patients in the VS during 1981-1996. Because of the large sample size, the authors were able to use multivariate methods to assess the effect of several risk factors on mortality. The authors found a strong secular trend in infant mortality, with rates in the mid-1990s being only one third of those in the early 1980s (P < 0.01). A smaller secular trend was observed for children aged 2-10 years and none for older patients. The mortality risk for older patients fell by approximately 8% for each year since the onset of the VS. The need for gastrostomy feeding was associated with a substantially higher risk, especially for infants and older patients (P < 0.01). Ventilator dependence also appeared to be a risk factor. On the basis of recent mortality rates, life expectancy in the VS is frequently higher than has generally been thought. For example, it is 10.5 additional years (+/- 2 years) for a 15-year-old patient who has been in the VS for 1 year, and 12.2 years for a 15-year-old patient who has been in the VS for 4 years.