Since being introduced in 1967, numerous models have been produced, often featuring a more powerful engine or a five-bladed main rotor in place of the original four-blade counterpart.

The Hughes 500/MD 500 series can be traced back to the early 1960s and the issuing of a requirement for a Light Observation Helicopter (LOH) for the United States Army.

[3] Following a competitive tendering process, Hughes' Model 369 was selected as the winning bid, triumphing over rival submission from the helicopter manufacturers Bell and Hiller.

[4][5] The MD 500 series features shock-absorbing landing skid struts, a turboshaft engine mounted at a 45-degree angle toward the rear of the cabin pod, a fuel tank cell under the floor and the battery in the nose.

It has a short-diameter main rotor system and a short tail, which gives it an agile control response and also makes it less susceptible to weather-cocking.

[citation needed] It had a distinctive atypical teardrop-shaped fuselage, a feature that sometimes led to personnel referring to it as the "flying egg".

[10] Seeking to profitably produce the type, Hughes offered the machine at a more realistic unit price of $56,550, however, this bid was undercut by the redesigned Bell OH-58 Kiowa, a militarised version of the JetRanger series.

The MD 520N introduced a revolutionary advance in helicopter design, dispensing with a conventional anti-torque tail rotor in favor of the Hughes/McDonnell-Douglas-developed NOTAR system.

According to Flying magazine, it has been particularly popular in circumstances where the primary passenger and pilot are both in the front seats, as can be typical in aerial observation, utility, and law enforcement work.

[22] Once they had arrived in North Korea, efforts continued to be made to conceal their existence, and are believed to have been flown only sparingly at least for a large portion of their service life.

[22] The modified MD 500 helicopters were finally revealed by North Korea in an obviously visible manner, even to international observers, during the country’s annual Victory Parade held in Pyongyang on 27 July 2013, which commemorated the 60th anniversary of the end of the Korean War in 1953.

According to analysts, it is visible that the North Korea's fleet of MD 500s have been modified significantly so that they can function as light attack helicopters.