The third Album of Vocal ensemble Gregoriana — the second one of our series In illo tempore has been released. We have named it according to the liturgical season which it illustrates — Tempus nativitatis (Christmas season). The aim of the series In illo tempore is to revive the old Slovak musical manuscripts dated before 1600. These are codexes of plainchant as well as polyphonic vocal liturgical music. The Album Tempus nativitatis was made in cooperation with guest conductor Jan Mikušek, who directed our ensemble on our previous CD nova et vetera too. Sources of plainchant: Bratislava Antiphonary I [1] Bratislava Antiphonary IIb [6, 7, 11, 12, 14, 15] Bratislava Antiphonary IV [1, 8] Bratislava Missal I [4,16] Canon Blasius’s Psalter [5] Sources of polyphony: Anna Hansen-Schuman’s Codex [10, 13, 15, 18] Košice Polyphony Codex I [5] Košice Polyphony Codex II [9] Košice Polyphony Codex III [2, 3]