As part of a complex land transaction to allow Brigham and Women’s Hospital (BWH) to build a new $100 million research medical building, Harvard Medical School (HMS) earlier this month sold “at favorable rates” 31 houses it owned in Boston’s Mission Hill neighborhood to a local tenants association.

Prior to the sale HMS rented the units as affordable housing. As part of the sale, the tenants association guaranteed to continue to rent the units as affordable housing.

The overall transaction will ensure that no residents lose their homes as a result of the building of the new facilities, although a half dozen homes will be relocated in order to allow the building of the new facility. As part of the transaction, BWH has also promised to provide expanded services to local residents, such as job training and English lessons. The neighborhood is home to many low-income families.

HMS officials said Harvard participated in the transaction because of its close ties to BWH, which serves as one of HMS’ most important affiliated teaching hospitals. Many HMS faculty members work primarily at BWH, and the new building will be home to many of them.

Don Gibbons, the spokesperson for HMS, noted that for the past several years the school has worked cooperatively on planning future development in the Longwood Medical Area with the other medical facilities in the area. Harvard’s participation in this transaction came as a part of these discussions.

“We are very committed to helping out our affiliated institutions in their research mission,” said HMS spokesperson Don Gibbons.

While helping BWH served as the immediate cause of the transaction, the sale continues HMS’ longer-term move to exit the property management business.

The school in 1999 sold a large apartment complex it had owned in the neighborhood and earlier this year sold a nearby strip of commercial property.