A sanatorium (also sanitorium, sanitarium) is a medical facility for long-term illness, typically tuberculosis. Distinctions are sometimes made between a "sanitarium" (a hospital) and "sanatorium" (a kind of health resort), but this distinction appears to be disappearing.

A sanatorium is distinct from a psychiatric hospital. According to the Saskatchewan Lung Association, when the National Anti-Tuberculosis Association was founded in 1904, it was felt that a distinction should be made between the health resorts with which people were familiar and the new tuberculosis treatment hospitals: "So they decided to use a new word which instead of being derived from the Latin noun sanitas, meaning health, would emphasize the need for scientific healing or treatment. Accordingly, they took the Latin verb root sano, meaning to heal, and adopted the new word sanatorium" ^*.

In the early twentieth century, tuberculosis sanatoriums were common in the United States. The first tuberculosis sanatorium for blacks was Burkeville, Virginia's Piedmont Sanatorium. Waverly Hills Sanatorium, a Louisville, Kentucky tuberculosis sanatorium, was founded in 1911. It has become a mecca for curiosity-seekers who believe it is haunted ^*.