How can the prestige of research centres forming part of scientific co-authorship networks focused on Physiology and Pharmacology be measured? This paper attempts to answer that question on the basis of a bibliometric analysis of Spanish scientific production in these areas of research between 1995 and 2005 as listed in Thomson Reuters’ Science Citation Index Expanded. An affinity index is used to measure the asymmetric co-authorship relationships between any two institutions on the collaboration network to obtain the hub and authority values for the leading institutions. The spatial distribution of network nodes is mapped with the Kamada Kwai algorithm. The findings identify the centres of greatest prestige from the standpoint of co-authorship of scientific papers.