Defective trees are potential hazards to people and property in recreation areas. Most reported tree failures within recreation sites in the Rocky Mountain Region occur in lodgepole pine. Defective root systems account for the greatest percentage of failures. External indicators of defects are used to identify trees that may fail. Some tree species, particularly aspen, are highly susceptible to visitor damage; managers should restrict recreational development in such forest types. Old growth spruce-fir stands should also be avoided for developed sites. Systematic, annual, documented inspections of trees in recreation sites and corrective action are recommended to reduce hazards to the public.