Julia Dempsey was born in Salamanca, New York on 14 May 1856, one of six children in her family.

She took her vows as a member of the Sisters of Saint Francis of Rochester, Minnesota in 1878 and the order trained her as a teacher during her novitiate.

He noted that her surgical judgment was equal to that of any medical man and that she ranked first among all of his assistants.

[1] The eponymous phenomenon known as the Sister Mary Joseph nodule refers to a palpable nodule bulging into the umbilicus as a result of metastasis of a malignant cancer in the pelvis or abdomen.

She pointed Mayo's attention to the bulge, and he published an article about it in 1928, although the actual term was not coined until 1949 by Hamilton Bailey.