For successful prosecution of sex offences, defined elements that comprise each charge (such as the acts that occurred and offenders’ identities) need to be established beyond reasonable doubt. This study explored the potential benefit (from a prosecution perspective) of eliciting another type of evidence; evidence regarding the relationship between the victim and perpetrator that may explain the victim’s responses. Fourteen prosecutors representing every major Australian jurisdiction participated in individual interviews or a focus group where they were asked to reflect on the perceived relevance of relationship evidence in sex offence trials, and the potential impact of this evidence on court process and outcomes. All prosecutors gave strong support for the premise of including relationship evidence in victim and witness statements, as well as in suspect interviews; however, this type of evidence was not routinely being included in interviews or admitted in trials. The majority of the discussion centred on: (a) the benefits and prevalence of eliciting relationship evidence; (b) how relationship evidence is best elicited in police interviews; and (c) challenges in presenting relationship evidence at trial. Each of these areas, their practical implications and directions for future research are briefly discussed.