Purpose-We study particular structural and organisational factors affecting the formality of human resource management (HRM) practices in small and medium-sized enterprises (SMEs) in SouthEastern European (SEE) post-communist countries, in particular Serbia, Romania, Bulgaria and the Former Yugoslav Republic of Macedonia (FYROM) in order to understand the antecedents of formalization in such settings. Design/methodology/approach-Adopting a quantitative approach, this study analyses data gathered through a survey of 168 managers of SMEs from throughout the region. Findings-The results show that HRM in SMEs in the SEE region can be understood through a threefold framework which includes: degree of internationalisation of SMEs, sector of SMEs and organisational size of SMEs. These three factors positively affect the level of HRM formalisation in SEE SMEs. These findings are further attributed to the particular political and economic context of the post-communist SEE region. Research limitations/implications-Although specific criteria were set for SME selection, we do not suggest that the study reflects a representative picture of the SEE region because we used a purposive sampling methodology. Practical implications-This article provides useful insights into the factors which influence HRM in SMEs in a particular context. The findings can help business owners and managers understand how HRM can be applied in smaller organisations, particularly in postcommunist SEE business contexts. Originality/value-HRM in SMEs in this region has hardly been studied at all despite their importance. Therefore, this exploratory research seeks to expand knowledge relating to the application of HRM in SMEs in SEE countries which have their business environments dominated by different dynamics in comparison to western European ones.