AbstractThe Institute of Medicine has recently endorsed arguments put forward by John Appleby calling for mandatory sex selection against female offspring in the initial trials of mitochondrial replacement techniques. In this paper I argue that, despite this endorsement, the reasons offered by Appleby for mandatory sex selection are inadequate. I further argue that plausible revisions to Appleby's arguments still fail to convincingly defend such an intrusive policy. While I remain neutral about whether intending parents making use of mitochondrial replacement techniques ought to have access to sex selection, I conclude that to date the case for mandatory sex selection has not been satisfactorily made.