In Israeli jurisprudence there is a substantial difference towards mentally ill patients between the civil and penal law systems that goes well beyond differences required by their separate objectives. Mentally ill people dangerous to others due to their illness belong in the hospital, not in the community or in jail. The data gathered especially for this paper make it hard to escape the conclusion that contemporary practice in Israel does not accord with this objective. On the civil front, inaccuracy in predicting who is dangerous may lead to involuntary commitment of people who are not dangerous. On the criminal side, too few people are sent to the hospital in Israel and correspondingly too many to jail. Comparison with US data and practice shows that on the civil side prediction has been improved by using actuarial methods, while on the penal side more up to date definitions of mental illness have been adopted. Whatever the appropriate solution for Israel, surely the first requirement is recognition of the problem.