The Population Research Unit (PRU) is a section in the Faculty of Social Sciences, University of Helsinki in Finland.

The research of the unit covers a wide range of topics including health and mortality, population ageing, social disadvantage, and family dynamics. In addition to studies focusing on the Finnish society many studies are conducted in international collaboration with colleagues from other European countries, East-Asia and the United States. The Population Research Unit focuses on quantitative research and uses longitudinal register data, twin data and genetically informative data based on surveys, clinical samples as well as their different combinations from various countries.

The unit collaborates with doctoral seminar Population, Health and Living Conditions (a sub-programme of the Doctoral Programme in Social Sciences) that focuses on advanced quantitative social research. The unit received the highest recognition in the latest research and doctoral training assessment exercise at the University of Helsinki as an integral part of the former cross-disciplinary Centre for Population, Health and Society. The head of the Population Research Unit is Pekka Martikainen, Professor of Demography.