Sak Lek (Thai: สากเหล็ก, pronounced [sàːk lèk]) is a district (amphoe) in the northeastern part of Phichit province, central Thailand.

Neighboring districts are (from the south clockwise) Wang Sai Phun and Mueang Phichit of Phichit Province, Bang Krathum, Wang Thong and Noen Maprang of Phitsanulok province.

The minor district was established on 1 April 1995 by splitting of the tambon Sak Lek, Tha Yiam, and Khlong Sai of Mueang Phichit district.

[4] Sak Lek is the largest plantation of mayong chit (mango plum) in Thailand, especially at Wang Thap Sai Subdistrict with an area of approximately 2,000 rais (790.51 acres).

[5] The district is divided into five sub-districts (tambon), which are further subdivided into 44 villages (muban).