The Milan Metro (Italian: Metropolitana di Milano) is the rapid transit system serving Milan, Italy, operated by Azienda Trasporti Milanesi. Milan metro is the longest metro system in Italy. The network consists of 4 lines, identified by different numbers and colors, with a total length of 92 km (57 mi) and a total of 101 stations, mostly underground. It has a daily ridership of over 1 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, the yellow line in 1990, and the lilac line in 2013. Current expansion of Line 5 and part of the new Line 4 are planned to open before the 2015 Expo.