Using the phenomenon of friendship as a case, the possibilities of a neurosemiotics of friendship is investigated by analysing ongoing research in cognitive social neuroscience on friendship. Neurosemiotics, both as a field dealing with particular semiosic processes that are neurobiologically based, and as an approach to the knowledge gained in neuroscience interpreting its semiosis of inquiry and dissemination, can help us better understand the construct of friendship having a neural basis. Thus, the finding that "neural similarity predict friendship", analysed as an instance of a propositional dicisign, can be true or false, depending on how prediction and friendship is interpreted.