Tumor treating fields (TTFields) is a new non-invasive approach to cancer treatment. TTFields is low-intensity (1-5 V/m), intermediate frequency (150-200 kHz) alternating electric fields delivered locally to the tumour to selectively kill dividing cells and disrupt cancer growth. TTFields has proven safe and effective for newly diagnosed glioblastoma and is currently being tried for multiple other tumours. This review presents an introduction to TTFields, covering the main indications, the application method, the mechanism of action, the clinical results and the perspectives for implementation in Danish cancer treatment.