A machine pistol shares several properties of the semi-automatic handgun and the sub-machine gun. Machine pistols are ordinarily clip-fed and self-cocking. Such a pistol is designed to be held and used in a single hand but almost always requires the use of both hands to control.

Originally machine pistol derived from maschinen pistole, the German term for the sub-machine gun. Today it is more often used to describe very small sub-machine guns such as the MAC-10 and the mini-Uzi, although the line between machine pistols and sub-machine guns is quite blurry. Additionally some fully automatic handguns such as the Glock 18 and obsolete Mauser C96, would qualify as machine pistols.

The Germans were the first to pioneer the machine pistol with the Schmeisser-designed Bergmann MP18 in 1918. It was not until the Spanish Civil War however that the machine pistols' effectiveness was displayed in the hands of poorly trained soldiers. In 1937 the Ermawerke company was contracted by the German army to build a machine pistol for mass production. The result was the Maschinen Pistole 38, known erroneously as the Schmeisser.