EI Niš, short for Electronic Industry Niš (Elektronska industrija Niš) is a company with headquarters in Niš, Serbia. It originated in 1948 from the foundation of the Institute for the Production of Radio Sets and Roentgen Machines, "RR Niš." In 1970-s and 1980-s it was one of the greatest Yugoslavian companies employing over 10 thousand people. However, during the 1990-s most of the company business collapsed, due to lack of investing in research and sanctions the country was facing.
Today, the company makes acoustic equipment, electronic tubes including cathode-ray tubes, printed plates, electronic machine elements, hydraulics, pneumatics, appliances, air-conditioners, medical equipment, roentgen machines, TV sets, radio receivers, and semiconductors. The company is also one of the few remaining makers of electronic vacuum tubes.
Until recently, the company was one of the few in the world to produce electronic tubes.