ENThe aim of this article is to present the concept and specificity of the borders and borderlands of Lithuania and its neighbours in the fifteenth and sixteenth centuries. The development phases of the Lithuanian state borders are presented and discussed in the context of the theory of border development. The states which bordered on the Grand Duchy of Lithuania: Poland, Muscovy, Livonian and German Order, Moldavia, Tatar hordes and – in the later period – the Ottoman Empire, offered different models of neighbourhood in terms of the regional cultural approach. The concept of state borders depended directly on the type of neighbourhood with another political entity and the border model was shaped by inter-state relations. The same state could have different border types with different border areas at the same time: both linear and non-linear or zonal ones. Linear state borders were finally formed after a military, socio-economic and cultural-ideological conquest of the area. The linear border model is applicable only to the northern and western borders of Lithuania. An internal colonization is regarded as the most important precondition for the creation of a linear border. Only as a result of a sufficient social and economic basis could the line dividing the states turn into a line which restricts the state area from the inside and from the outside. In the first half of the sixteenth century such a situation had already been established on the western and northern borderlands of the Grand Duchy of Lithuania. The border question was not resolved with Muscovy and the southern neighbours; natural circumstances had a significant impact on the internal colonization of the southern borderlands, this is why it is not possible to discuss changes of the borders during this period. [From the publication]