Hespanhol LC, et al. – The effectiveness of the online tailored advice addition was comprehensively analyzed to general advice on (1) the prevention of running–related injury (RRI) and (2) the determinants and actual preventive behaviour in Dutch trail runners. It was determined that online tailored advice prevented RRIs among Dutch trail runners. Hence, these could be used as a preventive component in multicomponent RRI prevention programmes. The determinants and actual preventive behaviours did not exert any effect.