The Burmese–Siamese War (1759–1760) was the first military conflict between the Konbaung dynasty of Burma (Myanmar) and the Ban Phlu Luang Dynasty of the Ayutthaya Kingdom of Siam. It reignited the centuries-long conflict between the two Southeast Asian states that would last for another century. The Burmese were "on the brink of victory" when they suddenly withdrew from their siege of Ayutthaya because their king Alaungpaya had fallen ill. He died three weeks later, ending the war.

The Ayutthaya Kingdom or the Empire of Ayutthaya was a Mon and later Siamese kingdom that existed in Southeast Asia from 1351 to 1767, centered around the city of Ayutthaya, in Siam, or present-day Thailand. European travellers in the early 16th century called Ayutthaya one of the three great powers of Asia. The Ayutthaya Kingdom is considered to be the precursor of modern Thailand, and its developments are an important part of the history of Thailand.