The aim of the paper is to answer the question how legal institutions which had originated under a radically different socio-economic system (i.e. actually existing socialism) became adapted to the new socio-economic system (i.e. a market economy). The paper argues that the condition of endurance of a legal survival is its functionality towards the requirements of the new system. Methodologically, the paper is based on the approach of case studies. It analyses five different legal survivals of the socialist period in Polish civil law (general part, property law and law of obligations) namely: the general clause of ‘principles of social life’; the general clause of ‘socio-economic purpose’; the in rem right of ‘perpetual usufruct’; the in rem ‘cooperative member’s proprietary right to an apartment and, finally, the agricultural procurement contract. The method of reasoning applied in the article is inductive, i.e. the conclusions are drawn from a generalisation of findings with regard to the specific case studies. The case studies are analysed both by resorting to dogmatic research, as well as socio-legal research on the basis of available literature.