Initial unsolicited report received from the literature on 12 November 2015. This case is linked to 2015SA184887, 2015SA184911, 2015SA188405, 2015SA188407 and 2015SA188408 (same literature). Since 2012, three clusters of serogroup C meningococcal disease among men who have sex with men (MSM) have been reported. During 2012, 13 cases of meningococcal disease among MSM were reported by a Department of Health and Mental Hygiene (1); over a 5-month period during 2012-2013, another Department of Public Health reported four cases among MSM; and during May-June 2015, a third Department of Public Health reported seven cases of meningococcal disease among MSM in that area. MSM have not previously been considered at increased risk for meningococcal disease. Determining outbreak thresholds for special populations of unknown size (such as MSM) can be difficult. The first health department declared an outbreak based on an estimated increased risk for meningococcal infection in 2012 among MSM and human immunodeficiency virus (HIV)-infected MSM compared with city residents who were not MSM or for whom MSM status was unknown (1). Another Department of Public Health also declared an outbreak based on an increase in case counts and thresholds calculated using population estimates of MSM and HIV-infected MSM. Local public health response included increasing awareness among MSM, conducting contact tracing and providing chemoprophylaxis to close contacts, and offering vaccination to the population at risk (1-3). To better understand the epidemiology and burden of meningococcal disease in MSM populations and to inform recommendations, CDC analyzed data from a retrospective review of reported cases in January 2012 through June 2015. In May 2013 and again in August 2015, CDC requested that health departments review all cases of probable or confirmed meningococcal disease caused by any serogroup and reported among males during January 2012-June 2015 to the Surveillance System and, if possible, determine MSM status. The requests were made through a secure communications network for public health officials, and follow-up with each health department occurred through individual e-mail correspondence. All health departments and the health departments of specific cities responded to CDC's request for information. Analysis of the data was restricted to cases occurring among MSM aged 18-64 years. During the case review period, 527 meningococcal disease cases among males aged 18-64 years were reported. Although MSM status is not routinely collected as part of national meningococcal case reporting and might be underreported, 74 cases were identified among MSM: 23 from one city, 14 from another, 11 from yet another, and 26 sporadic cases occurring in geographic areas where fewer than three cases of the same meningococcal serogroup were reported among MSM during a 3-month period. MSM status could not be verified for the other 453 meningococcal disease cases among men aged 18-64 years using available data, nor could CDC distinguish between health departments reporting zero cases in MSM and those that had no data on MSM status. Among the 74 reported cases among MSM aged 18-64 years, the median age was 31 years (range is equal to 20-59 years). Thirty-seven (52 percent) of 71 patients were one race, 29 (41 percent) were another race, two (3 percent) were yet another race, and three (4 percent) were other race. Neisseria meningitidis serogroup C accounted for 62 (84 percent) cases; serogroup B, W, and Y accounted for five, two, and three cases, respectively; and the serogroup for two patients was unknown. Overall, 24 (32 percent) cases were fatal, including six of the cases from one city (26 percent), five (36 percent) of another city cases, three (27 percent) of the other city cases, and 10 (38 percent) of the sporadic cases. Among 63 patients for who HIV status was reported, 37 (59 percent) were HIV-positive; among these, 11 (30 percent) died. Meningococcal vaccination status was known for 41 patients; among these, six (15 percent) were vaccinated with a quadrivalent meningococcal vaccine. Five of the six vaccinated patients had serogroup C meningococcal disease, and two of the five died. Further analysis of meningococcal disease rates, risk factors, and pulsed-field gel electrophoresis data from all cases identified among MSM is ongoing. Information on MSM and HIV status of men reported with meningococcal disease is not currently noted on most meningococcal case report forms. However, representative and complete data on MSM and HIV status are needed to better understand the epidemiology of and potential risk factors for meningococcal disease among MSM and to inform prevention and control recommendations. Health departments are encouraged to attempt to determine MSM and HIV status during investigations of meningococcal disease cases caused by any serotype occurring among males aged 16 years. This case involves one of the six male patients (age group between 18-64 years) who was vaccinated with a dose of Quadrivalent meningococcal vaccine (Manufacturer: unknown, batch number, expiration date, dose, dose number, route and site of administration were not reported) on an unspecified date. Medical history included Homosexuality (Men Who Have Sex With Men) and concomitant medication were not reported. The HIV status of the patient was not reported. On an unspecified date following the vaccination, the patient developed serogroup C meningococcal disease. Laboratory investigation and corrective treatment were not reported. The outcome of the event was not reported. Upon internal review, company assessed the event of serogroup C meningococcal disease as serious and important medical event. List of documents held by sender: none.