Windows NT 4.0係微軟Windows NT家族嘅第四套產品，代號Cairo，喺1996年7月29日發行給製造商。為一個32位元嘅作業系統，分為工作站以及伺服器版本。而佢嘅圖形操作界面同Windows 95差唔多。根據比爾蓋茲所言，產品名稱入面嘅"NT"為"New Technology（新技術）"嘅意思，然而時至今日，呢個名已經冇咩特殊意義存在。
Windows NT 4.0 is the fourth set of products in Microsoft's Windows NT family, codenamed Cairo, and was released to manufacturers on July 29, 1996. It is a 32-bit operating system, divided into workstation and server versions. And its graphical interface is similar to that of Windows 95. According to Bill Gates, the name of the product is a reference to uranium New Technology, but today, the name has no special meaning.