Thе article aims to present the development of professional engineering associations in the Balkans, using the example of Bulgaria and Romania. Attention is mainly focused on the interwar period. From a comparative perspective, the changes in this process in both countries are traced. The differences between the two cases, determined by the specific conditions in Bulgaria and Romania, are outlined. One common feature is also observed. In their efforts to protect the interests of engineers, their associations gradually lost their voluntary character and by the end of the 1930s they handed over the representation of the profession to state-controlled organizations.