On July 7, 1920, the Kingdom of Romania issued the first 1 leu note. The banknote, printed in blue ink, measured 78 millimeters in width by 55 millimeters in height. Displayed on the obverse was an industrial landscape, a maid, and the note's value. Depicted on the reverse was the Capitoline Wolf, with the Romanian coat of arms above, and portraits of Decebalus and Trajan at the wolf's left and right flanks, respectively.
On January 26, 1952, the People's Republic of Romania (RPR) issued a 1 leu banknote. It was brown and yellow in color and measured 118 millimeters in width by 57 millimeters in height. The obverse displayed the value, which was surrounded by ornate floral designs. Displayed on the reverse was the coat of arms of Romania, flanked to the right and left by the value.
On November 1, 1966, the Socialist Republic of Romania (RSR) introduced the third Romanian 1 leu note. Like the previous note, it was printed using brown and yellow ink. It measured 103 millimeters in width by 52 millimeters in height. On the obverse was the coat of arms of Romania with the value (as "UN LEU") underneath. The value was also depicted on the reverse, as a number and in words.