The study of demographic processes and phenomena, identifying their trends and patterns, as well as the implementation of various practical developments (forecasts, programs) requires the use of significant amounts of information about the population. The main sources of primary demographic data are: censuses, current records of demographic events, special sample surveys, lists and registers of the population. Based on the fact that the stated topic assumes a study of the dynamics of the movement of the Ukrainian population of the Republic of Moldova, we will conduct a comparative analysis of demographic information obtained from census data from 1959, 1979, 1989 and 2004. Let us dwell on the last of them (2004). The most important is the information about the ethnic composition of the population. Here we find data on the total number of Ukrainian population, their distribution by area (urban and rural), the native language of Ukrainians, the language they usually speak, etc. It is important that the ethnic composition of the population is represented by district and separately for each locality. This allows us to specifically determine the regions of compact and dispersed settlement of Ukrainians. Additional sources ─ data from the “Center of State Information Resources “Registru””; annual statistical compilation of the National Bureau of Statistics; data from the centers of Civil registry; military credentials, etc. are used. It is necessary to note such an important source of information as the materials of ethnographic research. They will help to identify the causes of some demographic processes based on the characteristics of the national traditional culture (family traditions, traditional medicine, traditional pedagogy, etc.).