Munster Irish (endonym: Gaelainn na Mumhan, Standard Irish: Gaeilge na Mumhan) is the dialect of the Irish language spoken in the province of Munster. Gaeltacht regions in Munster are found in the Gaeltachtaí of the Dingle Peninsula in west County Kerry, in the Iveragh Peninsula in south Kerry, in Cape Clear Island off the coast of west County Cork, in Muskerry West; Cúil Aodha, Ballingeary, Ballyvourney, Kilnamartyra, and Renaree of central County Cork; and in an Rinn and an Sean Phobal in Gaeltacht na nDéise in west County Waterford.

The north and west of Dingle Peninsula (Irish: Corca Dhuibhne) are today the only place in Munster where Irish has survived as the daily spoken language of most of the community although the language is spoken on a daily basis by a minority in other official Gaeltachtaí in Munster.

Historically, the Irish language was spoken throughout Munster and Munster Irish had some influence on those parts of Connacht and Leinster bordering it such as Kilkenny, Wexford and south Galway and the Aran Islands.

Munster Irish played an important role in the Gaelic revival of the early 20th century. The noted author Peadar Ua Laoghaire wrote in Munster dialect and stated that he wrote his novel Séadna to show younger people what he viewed as good Irish:

Ag machtnamh dom air sin do thuigeas am' aigne ná raibh aon rud i n-aon chor againn, i bhfuirm leabhair, le cur i láimh aon leinbh chun na Gaeluinne do mhúineadh dhó. As mo mhachtnamh do shocaruigheas ar leabhar fé leith do sgrí' d'ár n-aos óg, leabhar go mbéadh caint ann a bhéadh glan ós na lochtaibh a bhí i bhformhór cainte na bhfilí; leabhar go mbéadh an chaint ann oireamhnach do'n aos óg, leabhar go mbéadh caint ann a thaithnfadh leis an aos óg. Siné an machtnamh a chuir fhéachaint orm "Séadna" do sgrí'. Do thaithn an leabhar le gach aoinne, óg agus aosta. Do léigheadh é dos na seandaoine agus do thaithn sé leó. D'airigheadar, rud nár airigheadar riamh go dtí san, a gcaint féin ag teacht amach a' leabhar chúcha. Do thaithn sé leis na daoinibh óga mar bhí cosmhalacht mhór idir Ghaeluinn an leabhair sin agus an Béarla a bhí 'n-a mbéalaibh féin.

Peig Sayers was illiterate, but her autobiography, Peig, is also in Munster dialect and rapidly became a key text. Other influential Munster works are the autobiographies Fiche Blian ag Fás by Muiris Ó Súilleabháin and An tOileánach by Tomás Ó Criomhthain.

Munster Irish differs from Ulster and Connacht Irish in a number of respects. Some words and phrases used in Munster Irish are not used in the other varieties, such as:

The phonemic inventory of Munster Irish (based on the accent of West Muskerry in western Cork) is as shown in the following chart (based on Ó Cuív 1944; see International Phonetic Alphabet for an explanation of the symbols). Symbols appearing in the upper half of each row are velarized (traditionally called "broad" consonants) while those in the bottom half are palatalized ("slender"). The consonant /h/ is neither broad or slender.