The aim of this paper is to present the institutions of the scientific branch of information science in the Republic of Croatia, ie to present the development, work, goals, mission and information services of libraries, museums and archives. Libraries, museums and archives have played an important role in the development of knowledge and science throughout history and in preserving and protecting it. All the material and business are from the social, scientific and cultural good. The goal of these institutions is to inform, educate, encourage and link users with their own heritage as well to support the cultural, social and economic development of the community, to provide services, to provide free access to knowledge. We also see the impact of digitalisation on the business but also on the materials that these institutions possess. The digital era changes relationships between institutions and creators, as well as between institutions and users; all this affects the role and operations of institutions that should be fulfilled in society. Digitalisation enables the transformation of the material into a digital form and, together, it extends the services and functions of the institution. This paper presents the activities, historical development and information services of the mentioned institutions. The legal provisions regulating the operations of the institutions of the Republic of Croatia are also presented and provide basic definitions and classification of their business. The paper provides a brief historical review and development of institutions both in the world and in our areas.