Polar substorms include substorms observed at geomagnetic latitudes above 70° MLAT in the absence of simultaneous negative magnetic bays at lower latitudes, that is, substorms on the compressed contracted auroral oval. The general morphological features of polar substorms are considered based on the example of individual events registered on Svalbard arch. It is shown that polar substorms, like “classical” substorms, are characterized by the formation of a substorm current wedge and a steplike movement to the pole after the onset of a substorm, generation of Pi2 geomagnetic pulsations, and an increase of the PC-index of the polar cap before the onset of the substorm. At the same time, there are certain differences between polar substorms and “classical” substorms; namely, they start on more distant L-shells, develop in the region of a contracted auroral oval, occur at earlier pre-midnight hours, and generate only at low solar wind speeds and weakly disturbed geomagnetic conditions. It has been suggested that polar substorms may be a specific type of “classical” substorms that develop in the evening sector under magnetically quiet or weakly disturbed conditions when the auroral oval is concracted. The source of polar substorms may also be a local intensification of previously existing substorms in the post-midnight sector.