The Llangollen International Musical Eisteddfod is a music festival which takes place every year during the second week of July in Llangollen, North Wales. It is one of several large annual Eisteddfodau in Wales. Singers and dancers from around the world are invited to take part in over 20 competitions followed each evening by concerts on the main stage. Over five thousand singers, dancers and instrumentalists from around 50 countries perform to audiences of more than 50,000 over the 6 days of the event.

Famous performers at Llangollen have included Luciano Pavarotti (who first competed in Llangollen in 1955 with his father and a choir from their home town Modena, and for whom the Eisteddfod's principal trophy – the Choir of the World Pavarotti Trophy – is named), Red Army Ensemble, Julian Lloyd Webber and Ladysmith Black Mambazo. The final Sunday Evening Gala Concert has featured Katherine Jenkins, Bryn Terfel, Kiri Te Kanawa, James Galway and Montserrat Caballe.

The origins of the International Eisteddfod go back to 1943, when Harold Tudor, an officer of the British Council, arranged a visit for members of governments-in-exile to the Welsh National Eisteddfod in Bangor. The excursion was well received, especially by the noted writer and poet Juraj Slavik, the Minister for the Interior in the Czechoslovakia government-in-exile. Following the visit he wrote to Tudor praising the value of music as a way of healing the effects of war. The following year an international concert was held as part of the Llandybie National Eisteddfod.

Towards the end of 1945 Tudor proposed that an international choral festival be added to the 1947 Welsh National Eisteddfod; however, the Council of the National Eisteddfod felt that as all their effort was directed to rebuilding their own organisation, they could not take on such a scheme. Tudor modified his proposal into an independent music festival, and found support for this idea from W. S. Gwynn Williams, Welsh composer and music publisher, and George Northing, a teacher from Ysgol Dinas Brân and chairman of Llangollen town council. Gwynn Williams and Northing both pressed for the Eisteddfod to be in their home town of Llangollen.

The public gave support to this idea at two public meetings in May 1946, but concerns were also raised about who would come, where the event would be held and how the event would be financed. The British Council offered to help find choirs from Europe and to give financial support; however, the town decided to raise the money through a public subscription, and quickly gathered over £1100. George Northing was appointed as director of the executive board; Gwynn Williams became music director; Harold Tudor was director of publicity; and W. Clayton Russon, a local businessman and High Sheriff of Merionethshire, became president.

Plans to hold the event on the school field of Dinas Brân County School progressed throughout 1946-47. Accommodation for the overseas competitors would be in houses in the town and surrounding area, and domestic participants would be given beds in church and school halls. As rationing was still in place, ration coupons had to be found for all the visitors, and the Minister of Food was eventually persuaded to supply these.

In June 1947 it was time for competitors to travel to Llangollen, but a railway strike had started in France, and there was serious doubt as to whether any overseas competitors would be able to arrive. The organisers were relieved when the first coach of competitors arrived, bringing the ladies' choir Grupo Musical Feminino from Porto. They were the eventual winners of the Ladies Competition, whilst the Men's Competition was won by the Hungarian workers' choir, who had completed their journey to Wales by hitch-hiking when their train had been cancelled at Basel because of the French strike.

The Esperanto Society played a significant part in the first year, when it was felt that there could be a shortage of participants. Reto Rossetti, a well-known figure and author in the Esperanto movement, was asked to help, and through publicity in Esperanto magazines and to the surprise of the organisers, several groups contacted the Eisteddfod committee. Two troupes of Spanish dancers, on a tour of Britain sponsored by the British Council and the Esperanto Society, arrived and despite there not being a dance competition in the first year, performed to delighted audiences. Folk dance competitions have featured in every subsequent Llangollen Eisteddfod. The eisteddfod was brought to close with what has now become the traditional Sunday concert, featuring Sir John Barbirolli and the Hallé Orchestra. The 1947 International Eisteddfod was hailed as an unqualified success, with praise for the organisers, the founders, and all the competitors. There was even a surplus of £1,432 to be used for the next year's event.