Purpose of the article It is assumed that a strongly territorially concentrated branch that transformed into the sectoral agglomeration of identical companies in terms of the branches is specific for a range of its network ex-ternalities such as positive effects resulting from a qualified workforce, spreading innovation and transferring knowledge, experience and information. In general terms, some microeconomic factors and relevant variables will be perceived differently by ICT firms in the context of the different intensity of the sectoral concentration in the particular territory. Methodology/methods The contribution is based on the primary research performed among ICT companies in Moravskoslezský Region and Jihomoravský Region in the Czech Republic in 2016 and 2017 expressing their attitudes and opinions in the context of the branch concentration emphasizing the specific localization of these companies within the centres of the analysed regions, or on the outside, i.e. on the periphery. The analysis of the results from the questionnaire survey is in the empirical part confronted according to the location of the firms in the centres of ICT branch concentration of the chosen regions (in Brno-city and Ostrava-city) and simultane-ously compared across the two regions. The theoretical basis includes in particular "the core-periphery theory" and the New Economic Geography extended by the concept of the sectoral agglomerations and also selected theories of the period of post-Fordism.Scientific aim The presented contribution deals with the specification of the chosen microeconomic effects of the branch concentration of companies in the ICT sector of the given area, and defines differences in factors of the branch concentration of ICT companies. Findings Based on the performed research, it was discovered that more than 60 % of the companies perceive branch concentration positively and consider its effect beneficial and desired. From interregional comparisons follows