This paper aims to contribute to a better understanding of patent citation analysis in general and its application to novel fields of science and technology in particular. It introduces into the subject-matter by discussing an empirical problem, the relationship of nano-publications and nano-patents as representations of nano-science and nano-technology. Drawing on a variety of sources, different interpretations of patent citations are presented. Then, the nature of patent citations is further investigated by comparing them to citations in the scientific literature. After characterizing the citation linkage as indicators of reciprocal relationships between science and technology, patent citations in nano-science and technology are analyzed in terms of interfield and organizational knowledge-flows.