From the study of 143 bridge failures that occurred throughout the world from 1847 to 1975, it is found that there are nine categories of failure. The most frequent of these is failure due to flooding, because a single flooded river can destroy a whole series of bridges along its course. Other categories are brittle fracture, earthquake and wind failures, accidental destruction, falsework and steel box girder failures, and failures caused by corrosion and fatigue. For each category, one or more case histories is cited and discussed.