There is a perception that information systems security outsourcing, in spite entailing a relationship between a client and one or more providers, tends to be studied and analysed from the perspective of the client. A gap is then believed to exist in the study of the information systems security outsourcing relationship from the point of view of the service provider. This research aims to identify the key issues of such a relationship from the perspective of the service provider and rank them according to their importance. The Delphi method was used to support the communication with the group of experts contributing to this research as well as to boost consensus within the group. Final interviews with participants were also conducted with the aim of reaching deeper into their opinions and to shed a brighter light over the results of the Delphi. A ranked list of the 13 most important key issues found is presented and discussed and propositions for further work are put forward in the wake of the study.