The Romanian leu (ISO 4217 code RON; numeric code 946) is the currency of Romania. It is subdivided into 100 bani. The word "bani" is also used for "money" in the Romanian language.

The name of the currency means "lion", and is derived from the Dutch thaler (leeuwendaalder / lion thaler/dollar)

The Romanian leu has a history of instability. As such, the size and composition of coins has changed frequently.

In 1867, copper 1, 2, 5 and 10 bani were issued, with gold 20 lei (known as poli after the French Napoleons) first minted the next year. These were followed, between 1870 and 1873, by silver 50 bani, 1 and 2 lei. Silver 5 lei were added in 1880. Uniquely, the 1867 issue used the spelling 1 banu rather than 1 ban.

In 1900, cupro-nickel 5, 10 and 20 bani coins were introduced, with holed versions following in 1905. The production of coins ceased in 1914, recommencing in 1921 with aluminium 25 and 50 bani pieces. Cupro-nickel 1 and 2 lei coins were introduced in 1924, followed by nickel brass 5, 10 and 20 lei in 1930. In 1932, silver 100 lei coins were issued. However, inflation meant that in 1935, smaller silver 250 lei coins were introduced with nickel 100 lei coins being issued in 1936, followed by nickel 50 lei in 1937.

In 1941 and 1942, zinc 2, 5 and 20 lei coins were introduced, together with silver 200 and 500 lei. Nickel-clad-steel 100 lei followed in 1943, with brass 200 and 500 lei issued in 1945. In 1946 and 1947, postwar inflation brought the exchange rate even lower, and a new coinage was issued consisting of aluminium 500 lei, brass 2000 and 10,000 lei, and silver 25,000 and 100,000 lei.

Despite the neutrality adopted at the beginning of World War I, Romania had to cope with substantial expenses related to the need to sustain the war preparations. The expenses were covered by the public debt raised internally and externally. The national currency’s gold convertibility was not suspended, but limited to certain coins, with the exception of those in high demand (the napoleon and the gold sterling pound). To avoid silver speculations, the NBR put into circulation 1, 2 and 5 lei banknotes.

The inflation that had started at the end of the neutrality period was strongly felt after Romania had entered the war in 1916. Initially, this was triggered by the suspension of the banknotes’ convertibility on 12 April 1917, thus marking the end of the monometallic gold standard in Romania. Another cause was the printing of NBR uncovered issues, as requested by the government in order to cover the war expenses. The phenomenon was also influenced by the authorization given by the Ministry of Finance to issue paper money.

At the end of 1916, the German Military Administration (GMA) settled in Bucharest after it was evacuated by Romanian authorities. The same year, the representatives of the Central Powers decided in Berlin to issue paper money for the occupied territory of Romania. The General Romanian Bank (GRB), a bank with German capital established in 1895, was designated the issuing institution. The entire volume of the issue would be covered by a deposit especially constituted at the central German bank (Reichsbank), at the rate of 80 imperial marks = 100 lei. At the end of the war, the deposit had to be covered by the Romanian government. In this way, the goods bought with GRB money by the occupation authorities were actually acquired for free.

The GRB money was printed in Berlin and had the following face values: 25 and 50 bani, 1, 2, 5, 20, 100 and 1,000 lei. The lei issued by the National Bank of Romania were still allowed, but the GMA had imposed a lower exchange rate by comparison to the GRB leu (1 NBR leu = 74 imperial marks). The difficulties in making the right calculations caused by the existence of two different exchange rates for the two types of lei had determined the GMA to match the rates. However, at the same time, the GMA had ordered the occupation military to make payments to the population only in GRB lei.