Finds of bricks and wall remains indicate that the area was already inhabited by the Romans. The first documented mention of Lerowe is for the year 1248, the name Kylchleren appeared for the first time in 1306 in the Habsburg Urbar. The name comes from the Old High German lewirouwo, which means "by the land of the graves near the water". In the Middle Ages the village was in the domain of the Counts of Lenzburg, later the Counts of Kyburg. After these had died out, the Habsburgs took over the sovereignty and the blood jurisdiction in 1273.