The Office Building and Laboratory is a 2.5-story structure located at the west end of island 3.
It housed doctors' offices and a dispensary on the first floor, along with a laboratory and pharmacists' quarters on the second floor.
In 1924, the first floor offices were converted into male nurses' quarters.
A one-story morgue is located east of the office building, and was converted to the "Animal House" circa 1919.

An "L"-shaped powerhouse and laundry building, built in 1908, is also located on the west side of island 3.
It has a square north wing with boiler, coal, and pump rooms, as well as a rectangular south wing with laundry and disinfection rooms, staff kitchen, and staff pantry.
The powerhouse and laundry also had a distinctive yellow-brick smokestack.
Part of the building was converted into a morgue and autopsy room in the 1930s.

To the east are the eight measles pavilions.
All of the pavilions are identical, two-story rectangular structures.
Each pavilion held a spacious open ward with large windows on three sides and independent ventilation ducts.
A hall leading to the connecting corridor was flanked by bathrooms, nurses' duty room, offices, and a serving kitchen.

The administration building for the Contagious Disease Hospital is a 3.5-story structure located on the north side of island 3's connecting corridor, in the center of the landmass.
It included reception rooms, offices, and a staff kitchen on the first floor; nurses' quarters and operating rooms on the second floor; and additional staff quarters on the third floor.
A one-story kitchen with a smokestack is located opposite the administration building to the south.

At the extreme eastern end of island three were three separate isolation pavilions, which contained (wards I-L) and a staff house.
These pavilions were intended for patients suffering from more serious infectious diseases, including scarlet fever, diphtheria, and a combination of either of these diseases with measles and whooping cough.
Each pavilion was a 1.5-story rectangular structure.
Wards I and K are located to the south of the connecting corridor while ward L is located to the north; originally, all three pavilions were freestanding structures, but covered ways were built between wards I and K and the center corridor in 1914.
There were also nurses' quarters in each attic.
The staff building.
located at the extreme east end of island 3's connecting corridor, is a 2.5-story building for high-ranking hospital staff.
Living and dining rooms, a kitchen, and a library were located on the first floor while bedrooms were located on the second floor.
The Office Building and Laboratory is a 2.5-story structure located at the west end of island 3. It housed doctors' offices and a dispensary on the first floor, along with a laboratory and pharmacists' quarters on the second floor. In 1924, the first floor offices were converted into male nurses' quarters. A one-story morgue is located east of the office building, and was converted to the "Animal House" circa 1919.
An "L"-shaped powerhouse and laundry building, built in 1908, is also located on the west side of island 3. It has a square north wing with boiler, coal, and pump rooms, as well as a rectangular south wing with laundry and disinfection rooms, staff kitchen, and staff pantry. The powerhouse and laundry also had a distinctive yellow-brick smokestack. Part of the building was converted into a morgue and autopsy room in the 1930s.
To the east are the eight measles pavilions. All of the pavilions are identical, two-story rectangular structures. Each pavilion held a spacious open ward with large windows on three sides and independent ventilation ducts. A hall leading to the connecting corridor was flanked by bathrooms, nurses' duty room, offices, and a serving kitchen.
The administration building for the Contagious Disease Hospital is a 3.5-story structure located on the north side of island 3's connecting corridor, in the center of the landmass. It included reception rooms, offices, and a staff kitchen on the first floor; nurses' quarters and operating rooms on the second floor; and additional staff quarters on the third floor. A one-story kitchen with a smokestack is located opposite the administration building to the south.
At the extreme eastern end of island three were three separate isolation pavilions, which contained (wards I-L) and a staff house. These pavilions were intended for patients suffering from more serious infectious diseases, including scarlet fever, diphtheria, and a combination of either of these diseases with measles and whooping cough. Each pavilion was a 1.5-story rectangular structure. Wards I and K are located to the south of the connecting corridor while ward L is located to the north; originally, all three pavilions were freestanding structures, but covered ways were built between wards I and K and the center corridor in 1914. There were also nurses' quarters in each attic. The staff building. located at the extreme east end of island 3's connecting corridor, is a 2.5-story building for high-ranking hospital staff. Living and dining rooms, a kitchen, and a library were located on the first floor while bedrooms were located on the second floor.
Ellis Island Immigrant Hospital