These guidelines for the treatment of persons who have or are at risk for sexually transmitted diseases (STDs) were updated by the Centers for Disease Control and Prevention after consultation with a group of professionals knowledgeable in the field of STDs who met in Atlanta on April 18–30, 2009. The information in this report updates the 2006 Guidelines for Treatment of Sexually Transmitted Diseases (MMWR 2006;55[No. RR–11]).