Objectives: Anticholinesterases include carbamate and organophosphorus (OP) insecticides and nerve agents. Release of these compounds can flood emergency departments (EDs) with large numbers of poisoned victims and worried individuals. It was hypothesized that despite the focus of disaster preparedness on large metropolitan areas, EDs in these cities would still report self-perceptions of deficiencies in preparedness for mass casualty incidents (MCIs) involving these chemicals.Design and setting: A secure and anonymous online survey was prepared and piloted, and E-mail invitations were sent to the physician directors of the 220 continuously staffed EDs in the 12 most populous incorporated cities in the United States.Results: Forty-six ED directors could not be contacted despite repeated attempts. Of the remaining 174 directors, eight declined and 89 took the survey, for a response rate of 51.1 percent. Fewer than 20 percent were very confident in the effectiveness of their training, and only 4.9 percent were very confident that drills had given them the preparation that they needed. Only 45.7 percent of reporting hospitals had a board-certified medical toxicologist to help in such an emergency. Almost two-thirds (73.6 percent) of those familiar with the online Radiation Event Medical Management (REMM) module from the National Library of Medicine and the National Institutes of Health thought that a chemical counterpart to REMM would be either moderately or very helpful for MCIs involving anticholinesterases.Conclusions: This study demonstrates that physician ED directors perceived marked deficiencies in their abilities to respond to this kind of toxicological emergency and suggests critical directions for remediation of these deficiencies.