The Milan Metro (Metropolitana di Milano in Italian) is the rapid transit system serving Milan, Italy, operated by Azienda Trasporti Milanesi. Milan metro is the longest metro system in Italy and it is longer than all other metro networks in Italy combined. The network consists of 3 lines, identified by different numbers and colors, with a total length of 83.3 km (51.8 mi) and a total of 94 stations, mostly underground. It has a daily ridership of over one million.

The first line, the red one, opened in 1964, making Milan the second city in Italy after Rome to have a metro system. The green line opened 5 years later and the yellow line in 1990. Two new lines are under construction and are planned to open before the 2015 Expo.