The article deals with the role of the Greek goddess Hera and her Roman counterpart, Iuno, in the poetic treatments of the myth of Argonauts. The focus is put especially on Iuno’s character development in Valerius Flaccus’ adaptation of the myth. Iuno’s character in this work has already been discussed by Werner Schubert in his fundamental study (1991), in which he pointed out the remarkable approximation of Iuno fabulosa and Iuno civilis. Referring to this study, the article emphasizes rather the literary development of Iuno’s character. It is shown that Valerius Flaccus portrays the highest goddess not only as a peculiar helper (socia), as suggested by Schubert, but also as a permanent participant in an intertextual dialogue with the epic poems of Homer and Apollonius Rhodius. Valerius Flaccus’ aim here is to invert his literary predecessors’ accounts in a subtle and witted way (as Debra Hershkowitz has already presented).