Tetanus is a life-threatening but preventable disease caused by the toxin of Clostridium tetani, a ubiquitous, spore-forming, gram-positive bacillus found in high concentrations in soil and animal excrement. Reported tetanus cases have declined >95%, and deaths from tetanus have declined >99% in the United States since 1947, when the disease became reportable nationally. To update a previous report and to determine the populations at greatest risk for the disease, CDC analyzed cases reported to the National Notifiable Diseases Surveillance System (NNDSS) during 2001--2008. This report summarizes the results of that analysis, which found that 233 tetanus cases were reported during 2001--2008; among the 197 cases with known outcomes, the case-fatality rate was 13.2%. Average annual incidence during that period was 0.10 per 1 million population overall and 0.23 among persons aged ≥65 years. Incidence among Hispanics was nearly twice that among non-Hispanics, a difference accounted for by 16 cases among Hispanic injection drug users (IDUs). Among the 92 patients for whom tetanus toxoid-containing (TT) vaccination status was available, 37 (40.2%) had received no doses of TT vaccine. Thirty (15.4%) of 195 patients had diabetes, and 27 (15.3%) of 176 were IDUs. Of 51 patients with an acute wound and a surveillance report complete enough to evaluate tetanus prophylaxis, 49 (96.1%) had not received appropriate prophylaxis. Tetanus remains a rare but life-threatening disease in the United States. Health-care providers should ensure up-to-date TT vaccination of all their patients, especially persons aged ≥65 years, persons with diabetes, and injection drug users.