The Latsos Piano Duo in the context of Medellín Metropolitan Theatre

Piano four hands (French: À quatre mains, German: Zu vier Händen, Vierhändig, Italian: a quattro mani) is a type of piano duet in which the two players play a piece arranged for four hands on the same piano simultaneously. A duet with the two players playing separate pianos is generally referred to simply as a piano duet or piano duo.

Music written for piano four hands is usually printed so that left-hand pages contain only the part for the pianist sitting on the left, while right-hand pages contain only the part for the pianist sitting on the right. The upper part (right) is called primo while the lower part (left) is called secondo.

According to the Grove Dictionary of Music and Musicians, there are two kinds of piano duet: "[pieces of music] for two players at one instrument, and those in which each of the two pianists has an instrument to themselves." In American English usage, the former is often referred to as a "piece for four hands", or "piano four hands". Grove notes that the one-piano duet has a larger repertory, but has come to be regarded as a modest, domestic form of music-making by comparison with "the more glamorous two-piano duet". The two-piano form is also referred to as a piano duo, although this term also refers to a set of two piano players who play together regularly (thus, duos play duets).

The piano duet came to popularity in the second half of the 18th century.