This study looked at persons 20-64 years old in an Arizona county & found that the mortality rate for the seriously mentally ill population was: more than twice the rate for the general population; at least double that of the general population in 7 of 8 categories studied; & greater for unnatural causes of death (accidents, suicides & homicides) than for natural causes. Even if suicide could be prevented, susceptibility of death from many other causes would remain remarkedly high. (10 refs.)