Data were obtained on all male indicted felony defendants in New York State for whom a court psychiatric report on dangerousness had been made between September 1, 1971, and August 31, 1972 (n=257). For each defendant, data were collected on the current criminal charge, the psychiatric finding regarding the dangerousness of each defendant, and on the final determination of dangerousness made by the court. Data were also obtained on all defendants over a 3-year followup period. These data centered on outcome measures of the defendant's actual behavior subsequent to the determination of dangerousness. Data on defendants' assaultiveness were obtained from the maximum security hospitals to which both those deemed dangerous and those considered not dangerous were sent (All subjects had been judged incompetent to stand trial.), from hospital readmission records, from inpatient records of all subsequent hospitalizations, and from subsequent arrest records. The data showed that the more serious the crime with which the defendant was charged, the more likely were the psychiatrists to reach a finding of dangerousness; however, only 11.5 percent of the reasons cited by the psychiatrist for a finding of dangerousness referred to the defendant's current charge. The major reasons given for findings of dangerousness were mental illness and antisocial behavior. In 86.7 percent of the cases, the psychiatrists' recommendations regarding dangerousness were accepted by the court. Findings further showed that those evaluated as dangerous by the psychiatrists proved to be no more dangerous than those evaluated as not dangerous. These findings apparently undermine the scientific basis for predicting dangerousness assumed by New York law and the courts, as well as the role of psychiatrists themselves. Tabular data and 26 references are provided.