The article examines the development of the concept of intellectual capital. The article uses Russian and foreign sources of information from 1969 to the present time. We have revealed that the greatest interest in study of the concept of intellectual capital by Russian scientists occurred in 2000–2004. During the early stages, the concept was largely associated with knowledge, skills, experience and abilities of the staff of the organization. However, from mid-1990s, English sources started to separate a person as the bearer of knowledge, experience and skills from the actual intellectual capital. The concept was expanded to include image, business reputation, relationships with suppliers and customers, as well as patents, technologies and trademarks. This change occurred about ten years later in Russian scientific literature. We have found that an understanding of the structure of intellectual capital has evolved in 1996–1997. This structure contains the so-called human capital, which is based on knowledge, experience, competencies and skills. Subsequent development of the concept is associated with dividing it into other types of capital, which are subject to independent study. These types of capital are called structural capital, human capital, consumer capital. They are studied as separate concepts. However, many authors try to abandon these terms in formulating the concept of intellectual capital. This study showed that intellectual capital is studied as a property, a system of relations, capital, people, abilities of people and the results of these abilities, from accounting and legal points of view. A quarter of the studied definitions indicate that intellectual capital can bring wealth, advantages, added value, increase value, income, profit, increase innovation potential and economic efficiency.