Most patients with spinal cord injury (SCI) develop neurogenic lower urinary tract dysfunction (NLUTD), one of the most devastating sequelae of SCI which ultimately can lead to renal failure. We urgently need an intervention that prevents NLUTD before irreversible damage occurs. Neuromodulation procedures are a promising avenue so that we investigate the effect of transcutaneous tibial nerve stimulation (TTNS) in patients with acute SCI. This nationwide randomized, sham-controlled, double-blind multicentre clinical trial includes all SCI centres in Switzerland (Basel, Nottwil, Sion, Zürich). Patients are randomly assigned to VERUM TTNS (active stimulation, n=57) and SHAM stimulation (n=57) groups in a 1:1 allocation using computer-generated permuted block randomisation lists stratified on study centre and lower extremity motor score. Daily 30-minute sessions are performed five times a week during an intervention period of 6-9 weeks. The primary outcome of this study is the success of TTNS to prevent neurogenic DO jeopardizing the upper urinary tract, assessed by urodynamics at 1 year after SCI or any earlier time point if DO treatment is necessary (study end). Secondary outcome measures are bladder diary parameters, clinical symptom scores assessed by standardized and validated questionnaires. Furthermore, neurophysiological and neuroimaging outcome measures are assessed as well as, biochemical and molecular changes. Tertiary outcome measure is the safety of TTNS. Before the actual start of the TASCI RCT, start-up activities will include a piloting phase on groups of healthy volunteers and patients. The goal during this phase is to evaluate the feasibility of the experimental setup, in particular for the TTNS and SHAM intervention, but also to test the setup of the different pre and post assessments (e.g. neurophysiology and neuroimaging tests). Groups of up to 15 participants each will be enrolled in a few consecutive pilot studies allowing for fine tuning and small adaptations in between, if appropriate.