This paper starts from the definition of a witness and his classification on eyewitness and hearsay witness. It explains procedural role of witness in the Croatian Criminal Procedure, especially incompatibility role of witness to the role of the accused and other procedural roles. The paper describes witnesses duties as a citizen and sanctions if they do not accomplish them. Also, space is given to exemptions from the duty to testify and is stated which persons and under which conditions are not obliged to testify. It describes each phase of the procedure and the way witness testimony is taken. In addition to duties, witnesses have certain rights such as the right to reimbursement of expenses, right to procedural assistants, the right to deny responses to a particular question and the right to withdraw the statemen. In some cases witnesses need protection to fulfill their civic duty of testimony. The paper noted which witnesses Croatian positive legislation is guaranteeing protection and how it is implemented. The last part is devoted to the assessment of the credibility of witness testimony and explains the principle of free evaluation of evidence. It points out the factors that influence the scope and accuracy of the statements and specify criteria which the court takes into account when evaluating whether the witness showed credible. The conclusion is that the court, if it takes into account all the specific circumstances of the case and the criteria for evaluating the statements, there may be proper and full assessment of credibility of witness testimony.