PurposeThe paper aims to discuss the expected changes 5G will bring to the assessment of active mobile network sharing agreements from a competition policy point of view.Design/methodology/approachThe paper distinguishes between current, early 5G networks and the fully-fledged 5G envisioned for the future, then focuses on the main competition concerns where 5G may bring the most significant changes in the evaluation compared to 4G.FindingsThe authors find that while network sharing for early 5G can be evaluated in a similar way to previous generations, fully-fledged 5G can raise new issues. The authors predict these main concerns to be service differentiation, cost commonality between the parties and the parties’ ability and incentives to grant access to critical inputs to downstream competitors. Due to the huge costs of 5G rollout, network sharing is set to become even more widespread than before. For each of the concerns, the authors show that they are not easy to substantiate and they may even become less serious than under 4G.Originality/valueTo the best of the authors’ knowledge, this paper is one of the first contributions to analyse the impact of fully-fledged 5G on mobile network sharing agreements’ competitive assessment.