The Blue House is a 4-storey balcony-type tenement block located at 72-74A Stone Nullah Lane, Wan Chai, Hong Kong. It is named after the blue colour painted on its external walls. It is one of the few remaining examples of tong lau of the balcony type in Hong Kong and is listed as a Grade I historic building.

The house was the original site of the second hospital 'Wah To Hospital' (aka "Wan Chai Kai Fong Hospital"), which was built in the 1870s in Wan Chai. The hospital, which provided Chinese medical services to local Chinese, was possibly the first hospital in the district.

After the hospital closed in 1886, the two-storey building was then used as a temple for Wah To, the revered Chinese physician from the Three Kingdoms period.

The building was demolished in 1920 and was built into four four-storey tenement blocks in 1922. After the Japanese occupation of Hong Kong in 1945. The building was subsequently used as a martial arts school and Dit Da clinic by Lam Cho, the adopted nephew of Lam Sai-wing.

The building was acquired by the government in the 1970s, and in 1990 the outer walls were painted blue, thus earning it the name Blue House.

All the upper floors of Blue House, apart from 72 Stone Nullah Lane, are timber structures. The two wooden stairs, with original elements intact, are well maintained.

The building was part of a HK$100 million plan, unveiled by the Housing Society and the Urban Renewal Authority, to preserve nine Chinese-style buildings in Wan Chai that were constructed during the 1920s.

The building has been preserved and revitalised in a traditional tea and medicine style.