The study objective was to analyze hazardous materials event and victim factors associated with transportation of victims to a health care facility, and evacuation or shelter-in-place of nearby populations. A retrospective review was conducted on hazardous materials events in Washington State from 1993 to 1997. Bivariate and multiple logistic regression were used to identify risk factors for transportation, evacuation, and shelter-in-place. Over five years, 2,654 victims from 457 events were reported, with 1,859 (70%) transported to a health care facility. Evacuation occurred in 279 (61%) events and shelter-in-place in 14 (3%) events. After excluding 14 deaths, regression analysis indicated that victims with trauma (OR 5.87, 95% CI 1.41-24.5), thermal burns (6.90, 1.15-41.3), dizziness/other CNS symptoms (1.59, 1.00-2.54), and headache (1.54, 1.01-2.35) were most likely to be transported. Chemical releases inside buildings (2.09, 1.06-4.10, compared with transportation events), and involving 3-5 victims (2.86, 1.54-5.31, compared to 1 victim) or > or =6 victims (8.74, 4.01-19.0), were most likely to involve evacuation or shelter-in-place. Events involving sulfuric acid (0.15, 0.05-0.49) and sodium hydroxide (0.19, 0.04-0.94) were least likely to involve evacuation or shelter-in-place. Prehospital decisions to transport victims to a health care facility and evacuate or shelter-in-place nearby populations are associated with event and victim factors. Further research is needed to determine if these factors also predict need for medical care or removal from exposure, and to develop evidence-based prehospital care protocols for hazardous materials exposure victims.