[3] Trains on the Lilydale line run in two three-car formations of X'Trapolis 100 trainsets.

The line was built to connect Melbourne and Ringwood with the rural towns of Croydon, Mooroolbark, and Lilydale, among others.

Since the 2010s, due to the heavily utilised infrastructure of the Lilydale line, significant improvements and upgrades have been made.

[6] Duplication from East Richmond to Hawthorn occurred less than a month after the Lilydale extension opened.

[8] Electrification occurred between Flinders Street and Box Hill in December 1922 and extended to Ringwood the following month, then to Croydon in November 1925, and to Lilydale in October 1925.

[12] This left a short section of double track on the upside of Richmond, but this was quadruplicated with the construction of a flyover in 1973.

Ringwood to Croydon was converted to automatic signalling in November 1973 and duplicated in June 1984.

[14] This brought the cost of train fares down, improving system accessibility to the public.

[19][20] In 2023, the level crossings at Union Road and Mont Albert Road were removed by lowering the rail line; Mont Albert and Surrey Hills stations were demolished and permanently closed on 17 February 2023 and a new station built in between, named Union, which opened on 22 May 2023.

[23][24][25][26] The final level crossing on the line, Cave Hill Road in Lilydale, was simply closed to car traffic, with an underpass being built for foot traffic, set to open in "spring 2024".

[31] Train services on the Lilydale line are also subjected to maintenance and renewal work, usually on selected Fridays and Saturdays.

Shuttle bus services are provided throughout the duration of work for affected commuters.

Sections of the line have been elevated or lowered into a cutting to eliminate level crossings.

The stations are a mix of elevated, lowered, underground, and ground level designs.

The Lilydale line uses X'Trapolis 100 electric multiple unit (EMU) trains operating in a two three-car configuration, with three doors per side on each carriage and can accommodate up to 432 seated passengers in each six car configuration.