Background The surgical treatment of liver tumours relies on precise localization of the lesions and detailed knowledge of the patient-speciﬁc vascular and biliary anatomy. Detailed three-dimensional (3D) anatomical information facilitates complete tumour removal while preserving a sufﬁcient amount of functional liver tissue. Methods We present an easy to use, clinically applicable navigation system for efﬁcient visualization and tool guidance during liver surgery. Accurate instrument guidance within 3D planning models was achieved with a fast registration procedure, assuming a locally rigid and temporarily static scenario. After deformations occurring during the procedure, efﬁcient means for registration updates are provided. Special focus was given to workﬂow integration and the minimization of overhead time. The navigation system was validated with nine clinical cases. Results Navigated surgical interventions were performed with a median time overhead of 16.5 min. The navigation technology had a median accuracy of 6.3 mm, improving anatomical orientation and the detection of structures at risk. Conclusions Successful application of the navigation technology to open liver surgery was achieved by minimizing the procedural complexity and optimizing integration within the existing surgical environment. The assumption of locally rigid patient registration was validated, and clinical evaluation shows clear beneﬁts for the surgeon.