Neisseria meningitidis is a leading cause of meningitis and sepsis worldwide. Since 1981, a tetravalent meningococcal polysaccharide vaccine has been available in the US but it has been limited to high-risk patients and outbreak settings. In 2005, a tetravalent polysaccharide meningococcal conjugate vaccine (MCV4) was licensed for routine use in the US.To assess the immunogenicity and safety of MCV4, and to extrapolate the anticipated clinical effectiveness of MCV4 using data from other polysaccharide conjugate vaccination programs.All published controlled studies of MCV4 immunogenicity, safety and cost-effectiveness are analyzed. Publicly-available clinical trial data and the Advisory Committee on Immunization Practices guidelines were also reviewed.MCV4 is as safe and immunogenic as the previously available polysaccharide vaccine, and seems to provide longer lasting protection against meningococcal disease. Long-term studies are continuing and will shed further light on the effectiveness of MCV4 at the population level.