Abstract: In order to improve a surgical DC power tool such that it can be operated, where applicable, under sterile conditions, in particular, using conventional DC voltage supplies, a surgical switch mode power supply for a surgical DC power tool is provided. The switch mode power supply includes a switch mode power supply circuit arrangement, a switch mode power supply housing and a circuit receptacle formed in the housing of the switch mode power supply for accommodating the circuit arrangement of the switch mode power supply. The housing of the switch mode power supply has a switch mode power supply interface which is designed in such a manner that it can be brought into engagement with and/or connected to an interface of the DC power tool provided for a mains-independent energy source. Furthermore, an improved surgical DC power tool having such a power supply is provided.