The Zagreb tram network, run by the Zagrebački električni tramvaj (ZET), consists of 15 day and 4 night lines in Zagreb, Croatia. Trams operate on 116.3 kilometres (72.3 mi) of metre gauge route. During the day every line runs on average every 5–10 minutes, but almost every station serves at least two routes. Nighttime lines have exact timetables averaging at about every 40 minutes. The first horsecar tram line was opened in 1891, and the first electric tram ran in 1910. Zagreb's tram system transported 204 million passengers in 2008.

The first electric tram track was opened on 18 August 1910. The horse-drawn trams were kept until a tram electric network was finished and then they were moved to Velika Gorica where they remained in use until 1937.

The oldest rolling units of the post-World War II tram system were the two-axle TMK 101 trams. Three prototype units were built by ZET workshops in early 1950s, and other 68 units until 1965 by Đuro Đaković factory, with 110 matching trailers. A few of them were replaced by GT6, but they were in regular use until the TMK 2200 series came. They started to be replaced in the 2000s (decade), as the TMK 2200 started going into operation, and by summer 2007 only about 15 of type 101 were still operational, serving only as a substitute for other vehicles. They were finally pulled out of service in the winter of 2008.