The purpose of this study was to determine the incidence of endodontic services provided to participants in a longitudinal cohort study. The "Florida Dental Care Study" was a prospective cohort study using a representative baseline sample of 873 dentate adults. An in-person interview and clinical dental exam were conducted at baseline, 24, and 48 months after baseline, with telephone interviews every 6 months between those times. Dental record information was abstracted afterward. Thirteen percent of participants received at least one endodontic procedure after baseline. Endodontic services constituted approximately 2% of all dental procedures performed. Conventional root canal therapy comprised 94% of the endodontic services and was approximately evenly distributed among anterior teeth, premolars, and molars. Retreatment and apicoectomy each accounted for 3% of the endodontic procedures. The most common self-reported reasons for the dental visit in which a root canal occurred were "toothache," "abscess," and "dental sensitivity." A significant percentage of persons received some type of endodontic treatment in this diverse adult sample. Dental abscesses or toothaches were the main reason(s) for endodontic treatment, but not all persons with these conditions during follow-up sought dental treatment of any variety.