Kedushah (Jewish Babylonian Aramaic: קידושה, romanized: qiddúšā, lit. 'sanctification > holiness') is the name of several prayers recited during Jewish prayer. They have in common the recitation of two Biblical verses, Isaiah 6:3 and Ezekiel 3:12. These verses come from prophetic visions in which angels sing praises to God.

There exist several variations of the kedushah, which appear in different contexts and have different laws. The best-known Kedushah is recited in the Amidah. Another is recited in the Yotzer ohr blessing and a third, the qiddusha de sedra (Jewish Babylonian Aramaic: קידושה דסדראַ, romanized: qiddúšā ḏ séḏrā, lit. 'sanctification of the order') is recited on various occasions including the conclusion of weekday Shacharit. In some versions of the kedushah, additional Biblical verses are added in the same format as the verses from Isaiah and Ezekiel.

The Kedushah is traditionally the third section of all Amidah recitations. In the silent Amidah, it is a short prayer; in the repetition, which requires a minyan, it is considerably lengthier. The recitation of Kedushah daily is a Babylonian custom; in the Palestinian tradition, the repetition of the Amidah would usually not include the Kedushah, with it added only on special occasions according to Soferim § 20. The liturgy varies among different communities and during different services, but they all hold in common three Bible verses (though translations vary):

All three of the verses cited above are recited as part of the congregational response to the hazzan. For the first verse, Isaiah 6:3, it is traditional for everyone to rise to their toes with each recitation of the word qaddosh (Hebrew: קָדוֹשׁ, lit. 'holy').

In the Mussaf services of Shabbat, Jewish festivals, and in some communities, the Shacharit service as well, an enhanced version of the Kedushah is recited, with additional praises in between the biblical verses. In the Mussaf service of Shabbat and festivals, a fourth verse is added: the opening line of the Shema. The opening line of the Shema is included in the Kedushah on Ne'ilah of Yom Kippur, and in the Ashkenazic rite (including the Chasidic rite) in all of the Kedushahs of Yom Kippur. Many sources describe the recitation of the Shema during Mussaf as a response to historical anti-Jewish decrees prohibiting reciting the Shema at the proper point of Jews’ religious service, but contemporary scholars have proposed a variety of other explanations, as well.

During the Kedushah of the Amidah, petitioners are expected to stand, if able.

Kedushah is recited whenever the Amidah is repeated—that is to say, during Shacharit, Mincha, Mussaf, and Ne'ilah, but not Maariv.

A second Kedushah is recited as part of the Yotzer ohr blessing, before the Shema. The only two verses recited here are Isaiah 6:3 and Ezekiel 3:12.