Phaisali (Thai: ไพศาลี, pronounced [pʰāj.sǎː.līː]) is a district (amphoe) in the eastern part of Nakhon Sawan province, Thailand.

Phaisali or locally well known as Khok Duea,[1] is an ancient city, as proven by Khmer remains in Tambon Samrong Chai.

There were also prehistoric burial sites found in Tambon Pho Prasat and Na Khom, contemporary with the famous Ban Chiang.

[3] Neighboring districts are (from the north clockwise): Nong Bua of Nakhon Sawan Province; Bueng Sam Phan and Wichian Buri of Phetchabun province; Khok Charoen, and Nong Muang of Lopburi province; and Tak Fa and Tha Tako of Nakhon Sawan.

The district is divided into eight sub-districts (tambons), which are further subdivided into 101 villages (mubans).