Abstract The karyotype structure and chromosomal polymorphism were studied in several European (European part of Russia and the Netherlands) and Asian (Siberia and Kazakhstan) populations of Chironomus luridus Strenzke, 1959. Inversion polymorphism was detected in six of the seven chromosome arms: three banding sequences detected in arm A, six sequences in arm B, two sequences in arm C, three sequences in arm E, five sequences in arm F, and two sequences in arm G. Only arm D was monomorphic in all studied populations. In total, 22 banding sequences were recorded in Ch. luridus; they form the banding sequence pool of this species. Thus, Ch. luridus can be regarded as a very polymorphic species. However, the European and Asian populations differed considerably in the levels of polymorphism: the Asian populations were less polymorphic, containing only 8 to 10 sequences, whereas the European populations had 11 to 16 sequences. The new banding sequences lurA3, lurB5, lurE3 were found in Asian populations, whereas the sequences lurB2, lurB3, lurB4, lurB6, lurE2, lurF1, lurF2a, lurF3, lurF4, and lurG2 аre lacked. The total level of inversion heterozygosity in the Asian populations was 12-25% versus 78-80% in the European populations.