Karyotypes of the genus Lasiochernes (Pseudoscorpiones, Chernetidae) are studied for the first time. The diploid chromosome numbers of males were found to be 2n = 61 in L. pilosus, 2n = 69 in L. siculus and 2n = 73 in L. cretonatus. Karyotypes of all species mainly consist of biarmed chromosomes; the sex chromosome system is XO. Remarkably, the X chromosome displays partial (L. cretonatus), or even total (L. pilosus), negative heteropycnosis during the spermatogonial metaphase.