Based on the analysis of data on the development of surgical treatment of brain aneurysms, the authors identified the pre-surgical, early and late surgical stages and the microsurgical stage of development of the treatment of brain aneurysms. The microsurgical stage includes two basic areas ‒ aneurysm microsurgery and reconstructive surgery of the vessel with aneurysm via its revascularisation. The paper seeks to identify key points in the development of microsurgical treatment of brain aneurysms, excluding reconstructive treatment, which requires a separate study. The development of the microsurgical stage is associated not only with the advent of the surgical microscope but also with the invention of corresponding instruments, microsurgical dissection techniques, and the creation and introduction of accessory equipment to improve the quality of the surgical procedure.