The ad hoc international criminal tribunals addressing the mass atrocities involving such extraordinary crimes like genocide, crimes against humanity and war crimes have developed a delicate and intricate judicial scheme of ‘delayed disclosure.’ Against the backdrop of the unique gravity of egregious atrocities, ‘delayed disclosure’ aims at respecting the fundamental interests of both the accused and the witnesses, which has turned out to be an exceptionally challenging judicial exercise. Striking a balance between the rights of the accused to have adequate time to prepare his defence on the one hand, the protection of identifying information of witnesses who may be subject to serious danger or threat requires highly disciplined judicial vigilance on the other. For the purpose of elucidating the demanding challenges involving the practice of ‘delayed disclosure,’ this paper explores the relevant rules and case law of the ICTY and the ICTR.