ENArticle is aimed to review Lithuanian fortification development in 16 – 17 C. Not all military objects of the period but only a few different fortifications that may at least partially reflect fortification development in the discussed period are reviewed. In 16 – 17 C, growing threat from neighbours determined a few fortresses and fortified manors constructed, towns fortified in the Polish-Lithuanian Republic. In the present territory of Lithuania, gentry financed fortress in Biržai, fortress and fortified town of Klaipėda built by Prussian school engineers, several fortified manors and field fortifications can be mentioned. The old Italian bastion fortification system born in Europe in the 15 C never reached Lithuania. Kaunas and Vilnius bastions and Kaunas defence wall constructed in the 16 – 17 C did not completely reflect the trends and the level of artillery development in the West. The new Italian bastion fortification system spread wide in the 2 half of the 16 C was used in the construction of Biržai (1575-89) and Klaipėda (2 half of 16 C) fortress situated in the present territory of Lithuania. The old-type Dutch bastion fortresses which gained popularity during Dutch liberation wars against Spain (1566-1609) reached Lithuania in the 2 half of the 17 C. Construction of this type of fortress started in Biržai, in 1662. Fortified manors constructed in the former Polish-Lithuanian Republic represent a separate type of fortification. Fortified Baltadvaris manor cannot be called bastion fortress. Siesikai manor had no bastion fortifications either. Panemunis manor fortifications can be considered as redoubt adapted to landscape peculiarities. Belvederis fortification can be attributed to the typical bastion-type field fortification of the 17 C adapted to the site.