Description:Most of transitional (former socialist) countries still suffer from underdeveloped market mechanisms. In order to provide support for development of modern market mechanisms for the market of agricultural products, government experts within the Ministry of Agriculture and Forestry designed institutional information support - Market Information System in Agriculture of the Republic of Croatia - TISUP. This system is organised in order to prevent one of the most important market failures - insufficient and delayed dissemination of information that is crucial for the normal functioning of the market. The paper explores the functioning of the whole system and provides a general conceptional framework for understanding both market information systems and markets of agricultural products in Croatia and some other relevant countries/regions.