Objective To analyze the trend of serogroup switching of Neisseria meningitides (N.meningitidis) strains in Guangdong Province.Methods 656 N.meningitidis strains,isolated from 1966 to 2009 in Guangdong Province were analyzed with constituent ratio.Results 447 N.meningitidis strains isolated from 1966 to 2001 were composed of serogroup A (22％),serogroup B(46％),serogroup C(6％) and other serogroup strains (26％); from 2002 to 2009,209 N.meningitidis strains were divided into four mainly groups,including serogroup A (28％),serogroup B (53％),serogroup C (13％) and other serogroup strains (6％).Proportion of N.meningitidis serogroup C strains isolated from invasive meningococcal cases increased from 0 to 22％,serogroup B strains increased from 15％ to 28％,meanwhile,serogroup A strains decreased from 85％ to 47％.Serogruop C strains from healthy carriers increased from 7％ to 11％,serogroup A increased from 9％ to 24％ and serogroup B increased from 53％ to 58％.Conclusion It has shown that proportion of serogroup C and serogroup B in N.meningitidis strains isolated either from invasive meningococcal cases and from healthy carriers had increasing trend.Serogroups of N.meningitidis were switching from A to B、C in Guangdong Province.