Currently, about 11,000 oribatid mites have been described, but chromosome numbers have been reported for only a few species. Furthermore, the oribatid mites are a valuable model for holocentric chromosomes in cytogenetic studies. The diploid chromosome number is generally 2n = 18 in oribatid mites, though some have 2n = 16 or 30. Although there are many studies on the morphology and systematics of Phauloppia lucorum (Koch, 1841) (Oribatida: Oribatulidae), there is no information about its karyotype or chromosome numbers. The aim of this study is to investigate the chromosome number, monoploid ideogram and detailed chromosomal measurements of P. lucorum. The diploid chromosome number of P. lucorum was found to be 2n = 12. The total haploid chromosome length and the average chromosome length were 7.39 mu m and 1.23 mu m respectively. The chromosome lengths varied from 0.91 to 1.67 mu m. In conclusion, these results are the first for the chromosome numbers and karyotype analysis for P. lucorum.