Mesolithic sites in modern Poland are mainly located in the southern part of the country. Radiocarbon dating of organic material, such as charcoals, wood, and peat, provide a time frame of human settlements in those regions, and dating of speleothems and peat formations provide information on climatic conditions and the timing of climatic change in the region. Here, we present the results of calibrated 14C ages from 3 main Mesolithic sites: Glanów, Chwalim, and Całowanie. Summary probability density distributions of the calendar ages were obtained, and time ranges were ascribed to the cultures in conjunction with archaeological information. These distributions also reveal the changes in human settlement.