12 sanitary districts were located within the territory now covered by the BMA, and were thus merged into the new metropolis: Min Buri, Bang Khen, Prawet, Lat Krabang, Nong Chok, Nong Khaem, Bang Kapi, Bang Khun Thian, Taling Chan, Rat Burana and Bang Khae.
There are 11 further sanitary districts no longer existing:
- Hot (ฮอด) in Chiang Mai province was a sanitary district from 1957-1964.
- Don Wai (ดอนหวาย) in Nakhon Pathom province was merged into Sam Phran in 1965, just one year after it was created.
- Non Sila (โนนศิลา) in Kalasin province, created in 1956, was abolished in 1968.
- Tha Pla (ท่าปลา) in Uttaradit province was originally created in 1957, abolished in 1970 and recreated in 1973.
- Bang Khu Lat (บางคูลัด) in Nonthaburi province was abolished in 1975, just two years after it was created.
- Sao Cha-ngok (สาวชะโงก) in Chachoengsao province was created 1965 and abolished in 1976.
- Ko Pha-Ngan (then spelled เกาะพงัน instead of เกาะพะงัน) in Surat Thani province was abolished in 1976 and recreated in 1990. It was originally created in 1973, when the sanitary district Ko Samui was split.
- In 1979 in Kanchanaburi province Si Sawat (ศรีสวัสดิ์) was abolished and Erawan (เอราวัณ) was created due to the construction of the Si Nakharin reservoir. Si Sawat was created in 1956.
- In 1984 the same happened with Sangkhlaburi (สังขละบุรี), also in Kanchanaburi province. A new sanitary district Wang Ka (วังกะ) was created near the Khao Laem dam. The original sanitary district was created in 1956.
- Wat Chalo (วัดชลอ) was created in 1957 and merged into Bang Kruai in 1994.
- Finally Chai Badan (ชัยบาดาล) in Lopburi province was the only sanitary district which was not upgraded to a thesaban tambon in 1999, and was instead abolished. It was created in 1956.