This article comes from Clinical Evidence (2000;3:350-357), a new resource for clinicians produced jointly by the BMJ Publishing Group and theAmerican College of Physicians—American Society of Internal Medicine.Clinical Evidence is an extensively peer-reviewed publication that summarizes the best available evidence on the effects of common clinical interventions gleaned from thorough searches and appraisal of the world literature. It became available in the United States late last year. Please see advertisement for more information or, alternatively, visit the web site at www.evidence.org. QUESTIONS: What are the effects of prophylactic antibiotics on risk of disease in people exposed to someone with meningococcal disease? What are the effects of antibiotics in people with throat carriage of meningococcal disease?