We examine the reduction in London Underground passenger journeys in response to the July 2005 bombings. Using entrance data for London Underground stations between 2001 and 2007, we incorporate demand and supply factors in a multivariate time-series regression model to estimate changes in passenger journeys between different Underground lines. We find that passenger journeys fell by an average of 8.3% for the 4 months following the attacks. This amounts to an overall reduction of 22.5 million passenger journeys for that period. Passenger journeys returned to predicted levels during September 2005, yet we find evidence of reduced travel until June 2006. Our estimates controlled for other factors, including reduced Underground service provision due to damage from the attacks, economic conditions, and weather, yet substantial reductions in passenger journeys remained. Around 82% of passenger journey reductions following the 2005 attacks cannot be attributed to supply-side factors or demand-side factors such as economic conditions, weather, or the summer school-break alone. We suggest that this reduction may partially be due to an increased perception of the risk of Underground travel after the attacks.