Abstract. In this essay some aspects of relationship between Galileo and Campanella are analysed. Campanella held the scientist in high esteem. After reading his Sidereus Nuncius he sent to him a long Latin epistle and in 1616 he wrote the Apologia pro Galileo, in defence of the right of Galileo to abandon Aristotelian philosophy in order to read directly from the book of nature. As it is well known, prophecy and astrology played an important role in the thought of Campanella. As far as Galileo is concerned, notwithstanding his rejection of prophetical themes, he had some competence and interest in astrology. Many friends wrote to him to ask for horoscopes and to solve astrological problems derived from the recently discovered stars. His personal curiosity is proved by his outlining nativities for his friends, daughters and himself.