Using pulse electrophoresis in controlled homogenous electric field we conducted molecular karyotyping of highly-productive and laboratory strains of Acremonium chrysogenum generating antibiotic cephalosporin C (cefC). Differences in size of several chromosomes of highly active strain CB26/8 compared to the wild-type strain ATCC 11550 were revealed. It was shown that chromosomal polymorphism in the highly active strain was not associated with alteration of localization and copy number ofcephalosporin C biosynthesis and transport genes. A cluster of "early" cefC biosynthesis genes is located on chromosome VI (4.4 Mb); a cluster of the "late genes", on chromosome II (2.3 Mb). Both clusters are presented as a single copy perA. chrysogenum genome in the wild-type and in CB26/8 producer strains. Based on comparative analysis of laboratory and industrial cefC producers, a karyotype scheme for A. chrysogenum strains of various origins was designed.