Pilgrim Hospital is a hospital in the east of Lincolnshire on the A16, north of the town of Boston near the mini-roundabout with the A52. It is situated virtually on the Greenwich Meridian and adjacent to Boston High School. The fenland area of Lincolnshire is covered by this hospital, being the county's second largest hospital after Lincoln County Hospital. It is managed by United Lincolnshire Hospitals NHS Trust.

The hospital has its origins in temporary premises which opened as the Boston Cottage Hospital in 1872. A purpose-built facility designed by William Henry Wheeler was built in Bath Gardens between 1874 and 1875. Additions included an outpatients' department completed in 1926, a nurses' home in 1934 and a maternity wing in 1936. The facility joined the National Health Service in 1948.

The first hospital in Boston, Boston Cottage Hospital, opened in September 1872, in two small cottages on Stanbow Lane; it cost £200 a year, and treated around 50 people in the first year.

Following a design competition held in 1961, a completely new building was designed by the Building Design Partnership, one of its earliest public buildings, under Sir George Grenfell-Baines.

The design was agreed in January 1963. Phase 1 involved 115 in-patient beds, the outpatients, a single-storey A&E and X-ray, and Physical Medicine. The five-storey 72-bed maternity department would be built in this phase, but would be initially part of outpatients, until the whole hospital had been later completed. The former maternity unit was at Boston General and Wyberton West (owned by the county council) hospitals.

There would be residential accommodation for around 150 nursing staff, to the north of the site, costing around £150,000.

The hospital name was chosen at a meeting in September 1967 at Holbeach Hospital; this name was chosen, as a snappy title would save significant time over the telephone, and avoid confusion. Many other possible names were rejected.

Around 23 student nurses joined the Boston School of Nursing, each year.