A deflection prism assembly for an endoscope having a lateral viewing direction, the deflection prism assembly including: a prism holder； and a deflection prism accommodated in the prism holder； wherein the deflection prism has a light outlet surface and an opposite light inlet surface arranged obliquely to the light outlet surface, the deflection prism further having a lateral surface extending between the light inlet surface and the light outlet surface； and the prism holder accommodates the deflection prism such that the prism holder surrounds less than all regions of the lateral surface of the deflection prism.
