The economic and social transformation of countries of central and eastern Europe has deeply affected their S&T systems. However,
conceptual and methodological problems in monitoring transformation of their S&T systems are not trivial. In this paper we
analyse conceptual and methodological issues involved in measuring S&T activities in the socialist and post-socialist period
across the most important S&T indicators (R&D, US and national patents; innovation surveys; bibliometrics). Our conclusions
are that: i) the process of methodological harmonisation of S&T indicators has progressed considerably and we have provided
some evidence in that respect; ii) the use of similar or identical indicators (business R&D, innovation counts, patents, citations)
when making inter-country or inter-temporal comparisons should be approached with caution because of the significant differences
between the socialist and post-socialist periods as well as between post-socialist R&D systems and R&D in other market economies.
This latter applies especially to the interpretation of business R&D data in the post-socialist period.