Previously, we have shown that pyruvate kinase, liver and red cell isoform (PKLR) deficiency protects mice in vivo against blood-stage malaria, and observed that reduced PKLR function protects human erythrocytes against Plasmodium falciparum replication ex vivo. Here, we have sequenced the human PKLR gene in 387 individuals from malaria-endemic and other regions in order to assess genetic variability in different geographical regions and ethnic groups. Rich genetic diversity was detected in PKLR, including 59 single-nucleotide polymorphisms and several loss-of-function variants (frequency 1.5%). Haplotype distribution and allele frequency varied considerably with geography. Neutrality testing suggested positive selection of the genein the sub-Saharan African and Pakistan populations. It is possible that such positive selection involves the malarial parasite.