Barysaw or Borisov (Belarusian: Барысаў, romanized: Barysaŭ, IPA: [baˈrɨsaw]; Russian: Борисов, IPA: [bɐˈrʲisəf]) is a city in Minsk Region, Belarus. It serves as the administrative center of Barysaw District. It is located on the Berezina River and 74 kilometres (46 mi) north-east from the capital Minsk. As of 2025, it has a population of 134,732.

The name Barysaw is the Belarusian equivalent to the Russian name Borisov. It may be an eponym derived from the given name Boris, possibly named after the 12th-century prince, Boris Vseslavich.

Barysaw is first mentioned in the Laurentian Codex as being founded (as Borisov) in 1102 by Rogvolod Vseslavich, Prince of Polotsk, who had the baptismal name of Boris. During the next two centuries, it was burned and then rebuilt south of where it was before.

From the late 13th century to 1795, the town was part of the Grand Duchy of Lithuania, which was part of the Polish-Lithuanian union since the Union of Krewo (1385) and the Polish–Lithuanian Commonwealth after the Union of Lublin (1569).

In 1500, during the Lithuanian–Muscovite War, Alexander Jagiellon resided in Barysaw Castle. In 1563, it was granted Magdeburg town rights by King Sigismund II Augustus.

In the last years of the Polish-Lithuanian Commonwealth, troops were stationed here, including the 2nd and 4th Lithuanian Vanguard Regiments and 1st Lithuanian Infantry Regiment. King Stanisław August Poniatowski established the town's coat of arms (decree #17435), the top half containing the coat of arms of Minsk, while the lower half had two stylized towers on a silver background with a passage between them and Saint Peter above the towers holding a key in his hand.

Barysaw became part of the Russian Empire in 1793 as a result of the Second Partition of Poland.

After the Partitions of Poland, Barysaw was an uyezd town in the Minsk Governorate.