Poverty lines are basic measurements of this phenomenon both in research and in praxis of social policy. They define limits of poverty, absolute and relative. One may point to objective or quasi-objective methods referring to the level and the structure of meeting basic needs of individuals and their families as well as subjective methods, based on the opinions of respondents on these questions. The article presents the most frequently used poverty lines and points to various methodological, economic and social conditions of their application. Some contemporary problems referring to using poverty lines in Poland were also presented in relation to the level and differentiation of population incomes.