The article “Diagnosis and Treatment of Chlamydia Trachomatis Infection,” (April 15, 2006, page 1411) contained an error in the dosage of erythromycin for persistent urethritis recommended by the Centers for Disease Control and Prevention (CDC). In the first paragraph of the right hand column on page 1413. The dosage for erythromycin was listed as being 500 mg orally twice daily for seven days; it should have been 500 mg orally four times per day for seven days. The sentence should have read: “If symptoms suggest recurrent or persistent urethritis, the CDC recommends treatment with 2 g metronidazole (Flagyl) orally in a single dose plus 500 mg erythromycin base orally four times per day for seven days, or 800 mg erythromycin ethylsuccinate orally four times per day for seven days.” The article has been corrected online.