Islamic law defines evidence as an evident indication of the commission of an offense by a certain person. This evidence can be either a testimony, a confession by the offender, a solemn oath taken by the plaintiff, or a testimony given by the plaintiff. The evidence required for a conviction differs from one offense to another. Some crimes require only two witnesses while others necessitate four witnesses (adultery, for example). Some crimes are legally proven only by oathtaking, such as in 'Qasamat' where 50 solemn oaths are taken by claimants to prove a punishable crime. Other crimes are proven by the testimony of the claimant, such as in 'Lia'an' when a husband accuses his chaste wife of adultery but has no witnesses to support his accusation. People are encouraged to participate as witnesses in the courts, and they are warned against concealing facts or committing perjury. The requirements for witnesses are that they be sane adult Muslims who are objective in their testimony. An unbeliever is not permitted to testify against a Muslim. Testimony by non-Muslims against other unbelievers is acceptable provided such testimony conforms to the witness' traditions and conception of justice. The testimony of children is acceptable provided such testimony has not been influenced by parents or relatives. The significance of circumstantial evidence is emphasized. This paper is discussed by symposium participants.