This paper deals with the aorist voice system in NT Greek and focuses on middle-passive markers, namely middle inflection, e.g. in the middle sigmatic aorist, and affixes -η-/-θη-, in the so-called passive aorist. The research is corpus-based and investigates the occurrences of ca. 1800 verbal items. According to the grammarians, in the NT both middle and passive aorists spread. The present study confirms this observation by providing a comprehensive account of the distribution of these forms, but also shows how they have functionally reorganised. Passive aorists spread at the expense of middle aorists in all kinds of intransitive constructions, namely passive, unaccusative, and reflexive, whereas middle aorists are either found in transitive middles, e.g. possessive, benefactive etc., or occur as deponent verbs in both transitive and intransitive clauses. The parameter transitive vs intransitive appears to be relevant for this functional reorganisation.