Multilocus sequence typing was applied to a collection of 327 clinical isolates of Klebsiella pneumoniae from China, which was proven to be a good representative of the global diversity of K. pneumoniae. Three lineages L1 to L3 are presented in the population with limited genetic flow across different lineages. However, extremely high levels of recombination can be observed within lineages to the extent at which the alleles are associated almost randomly. Lineages L2 and L3 most likely represent highly specific subgroups of less-virulent K. pneumoniae with modified metabolic networks, while lineage L1 contains not only hypervirulent clones with massive acquisition of virulent genes but also 'primitive and intermediate forms' during evolution of hypervirulent K. pneumoniae.