In modern business conditions, internal audit has significant potential for creating added value for the company and improving its operations. The extent to which internal audit will realise its objectives is primarily determined by the level of its effectiveness. In this regard, the authors of the paper, in addition to highlighting the importance of internal audit for achieving the strategic goals of the company, deal with the specifics of ensuring its effectiveness. These specifics are related to the issue of measuring the effectiveness of internal audit, as well as to identification and analysis of the factors that largely determine the achieved level of effectiveness of internal audit.