A range of In-Vehicle Information Systems are currently developed and implemented in trucks to warn drivers about road dangers and vehicle failures. Systems often make use of conventional repetitive auditory warnings to catch attention. In a critical driving situation it might be tempting to use signals that express very high levels of urgency. However, previous studies have shown that more urgent alerts can have a negative impact on the listeners’ affective state. A simulator experiment was conducted to examine how urgent warnings could impact the affective state of experienced truck drivers, and their response performance to an unpredictable situation. As predicted, the more urgent warning was rated more annoying and startling. The drivers who received an urgent warning braked significantly harder to the unpredictable event (a bus pulling out in front of the truck). The drivers also tended to brake later after the urgent warning, but no significant effect on response time or time to collision was found. A concluding recommendation for future research is to investigate distracting effects of urgent auditory warnings on less experienced drivers. Alternative URL: http://icad.org/Proceedings/2010/Fagerlönn2010.pdf