St. Alphonsus Hospital was a three-story, French Renaissance style building in Boise, Idaho, designed by architect J.K. Hollowell in 1893.

Completed in 1894, the hospital was part of a small group of buildings constructed by the Roman Catholic Diocese of Boise that included St. Teresa's Academy (demolished).

[6] Local doctors had treated patients at the building, but in 1896 the hospital acquired a staff of physicians and surgeons.

The hospital moved about three miles (5 km) west in 1972 to its present site on Curtis Road, just south of I-184.

Boise's other hospital, St. Luke's, was founded by the Episcopal Diocese of Idaho in 1902 and is located several blocks southeast of the Cenarrusa building.