We describe hematologic and DNA characterization of 12 hemoglobin C heterozygotes and three compound heterozygotes for hemoglobin C and hemoglobin E found in Thailand. Amplification and DNA analysis of genomic DNA by the polymerase chain reaction procedure permitted the identification of the β^C mutation at codon 6 of β‐globin gene (β 6; GAG–AAG). β‐Globin gene haplotype analysis demonstrated that all β^C globin genes detected in these Thai individuals were associated with the haplotype (+ − − − − − +), indicating a non‐African origin of this abnormal hemoglobin in Thailand. On routine hemoglobin typing, hemoglobin C is usually mistakenly identified as hemoglobin E because of theirs similar mobilities on cellulose acetate electrophoresis. The simple DNA assay for hemoglobin C based on an allele‐specific polymerase chain reaction for accurate diagnosis of hemoglobin C was therefore developed. Am. J. Hematol. 67:189–193, 2001. © 2001 Wiley‐Liss, Inc.