The Hospital's roots run deep, dating back to 1905 when the first Midland hospital was opened. The Midland/Penetanguishene Marine and General Hospital was located in Sunnyside. The hospital had 12 beds and the daily cost per patient was $.70. When in 1911, Penetanguishene built its own hospital, the name was shortened accordingly.

In the little isolated hospital building in Sunnyside, cows and chickens were kept and a large garden helped supply the kitchen. The nurses not only put in a twelve hour day, they were expected to do all sorts of chores in their spare time, such as kitchen duty, gardening and milking the cow. The hospital auxiliary was formed in 1906 by a group of enthusiastic women willing to offer support. Their chief responsibilities were supplying and sewing linens, gowns, layettes, table cloths and aprons.

In 1918 the hospital moved to the Manley Chew home on Bay Street in the town of Midland proper which was purchased as a gift to the town by Mr. James Playfair. He stipulated that it be named St. Andrew's Hospital. Mrs. Playfair, past president of the Auxiliary donated the house next door as a nurses' residence.

St. Andrew's Hospital remained home to Midland's hospital services until 1976. In the early 1970's funds were made available by the government and the County of Simcoe to plan the building of a modern, state-of-the-art hospital for residents of Midland, Tay and Tiny Townships and surrounding areas.

‘Huronia District Hospital’ opened to the public in October, 1976. The old hospital building was purchased and became a nursing home, keeping a portion of the old name as St. Andrew's Manor. In the late 1980's planning began to improve the hospital through expansion of the emergency department, obstetrics program and laboratory services. A capital campaign began in 1988, managed by the newly formed Huronia District Hospital Foundation raised over $2 million to make the necessary changes to HDH to meet volume increases.