A plasminogen probe encoding kringles 1-3 detects homologous loci on human chromosomes 6 and 2 by somatic cell hybrid analysis. Regional localization by in situ hybridization places the loci at 6q26-27 and 2p11-q11. Further analysis by varying washing stringencies of hybridization filters reveals a greater homology with the chromosome 6 locus than with the chromosome 2 locus. These results confirm localization of the plasminogen gene to human chromosome 6q26-27 and indicate that a homologous sequence of unknown identity resides on chromosome 2p11-q11.