Nei or NEI may refer to:
Nei, Iran, a village in Ardabil Province, Iran
Nei, a character in the Phantasy Star II roleplaying game
Nutrition and Education International
Nuclear Energy Institute, American nuclear industry lobbying group
National Eye Institute, one of the US Institutes of Health
Netherlands East-Indies, also known as the Dutch East Indies
Northern Engineering Industries, a defunct British engineering firm
Noise-equivalent irradiance, in astronomy
