The Irish Nurses and Midwives Organisation was originally founded in 1919 when a small group of nurses and midwives, came together, in Dublin, to address two issues namely:

An improvement in pay; and
The setting of professional standards for the performance of their duties.

The newly formed organisation, which was known as the Irish Nurses Union, actively recruited new members, in its early years, and made significant progress in relation to pay and pension, and the setting of standards through a range of educational initiatives e.g. lectures/policy documents.

In 1931 the new organisation began its work, on the international stage, by affiliating to the International Council of Nurses (ICN) and the INMO continues this affiliation to this very day.

In 1972 the then Irish Nurses Organisation (INO), now INMO, was a founding member of the Standing Committee of Nurses in the European Union (PCN). The INMO continues in active membership with this body which is now known as the European Federation of Nurses.

In 1978 the Organisation voted overwhelmingly to seek affiliation to the Irish Congress of Trade Unions (ICTU) and ten years later the necessary order was granted by the High Court for the Organisation to register as a trade union under the Trade Union Act 1941. The Organisation then made immediate application for affiliation to the ICTU and the affiliation process was completed in January 1990. Since then the Organisation has consistently been represented on the ICTU Executive Council, involved in all national negotiations, under the social partnership process, while also being an active participant in a range of other work initiated by ICTU on behalf of all workers.

In 2009 the Organisation celebrated its 90th Anniversary with a range of activities and events which recognised the constant growth of the Organisation, over the decades, and the fact that it was now the recognised voice of nursing and midwifery in Ireland.

On 1st January 2010 the Organisation changed its name to the Irish Nurses and Midwives Organisation in order to reflect, in its name, structures and rules, the following:

The imminent passage of legislation, in 2010, which will, for the first time, give legal recognition to the two separate, and distinct, professions of nursing and midwifery;and
The reality that, in 2010, Ireland will see the first graduates from our direct entry midwifery honours degree programme. This will mean that, in 2010, Ireland will have Registered Midwives, in clinical practice, who are not Registered Nurses