After Saint Brigid, Ita is the best-known female saint in Ireland. She is also known as Deirdre, Ida, Ide, Meda, Mida, or Ytha. Early biographers often called her the "Brigid of Munster," but her life was quite different from Brigid's - less peripatetic and more austere.

Ita was born to Christian parents in what is now the county of Waterford, around 480. She is said to have been of royal lineage. When her father sought to marry her to a nobleman, she fasted for three days in protest, praying all the while for divine help in avoiding the marriage. Help came in the form of an angel who appeared to her father and persuaded him that Ita must be allowed to live a religious life and remain a virgin.

Ita became a nun, and moved to a place that is now known as Killeedy (Church of Ita) in County Limerick. She founded a convent there, for which a local chieftain supposedly offered her a large land grant. Ita, however, accepted only four acres. Later she founded a nearby school for boys, where she educated many who later became eminent men of the early Irish Church. For this reason, she has been called "foster mother of the saints of Ireland."

When asked what three things were most pleasing to god, she reportedly replied, "True faith in God with a pure heart, a simple life with a religious spirit, and open-handedness inspired by charity." According to Ita, the things which God hates most are "A scowling face, obstinacy in wrongdoing, and too great a confidence in the power of money."

Many miracles were attributed to Ita. She is reputed to have re-joined the head of a beheaded man with his body. She is also said to have lived only on food from heaven. Regardless of whether or not these miracles happened, it is true that she spent a lot of time fasting and ministering to the sick in the area.

Ita lived a long life. She died around 570, perhaps from cancer. Legend says that a beetle devoured her side, growing to the size of a pig. The date of her death, January 15, is now kept as her feast. She is still widely venerated in Ireland, especially in Waterford and Limerick.