We report the first polymorphism of nucleolar organizer regions (NORs) and karyological analysis of the banded langur (Presbytis femoralis) from Thailand. Blood samples were taken from two male and one female langurs. After standard peripheral blood lymphocytes had been cultured at 27°C for 96 h in the presence of colchicine, the metaphase spreads were performed on a microscopic slide and air-dried. Conventional, GTG-banding and high-resolution techniques were applied to stain the chromosome. The results showed that the diploid chromosome number of P. femoralis is 2n = 44, and the fundamental numbers (NF) of both sexes is 88. The types of autosomes are 20 large metacentric, 8 large submetacentric, 2 large acrocentric, 2 medium submetacentric, 4 small metacentric, 4 small submetacentric, and 2 small acrocentric chromosomes. The X chromosome is a large submetacentric chromosome and the Y chromosome is the smallest submetacentric chromosome. In addition, the long arm near the centromere of chromosome pair 17 showed clearly observable NORs. The result showed different sizes of NORs for heteromorphic chromosome pair 17 of all males and female. From the GTG-banding and high-resolution techniques, the number of bands on one set of haploid chromosomes in the P. femoralis are 264 and 332, respectively; each chromosome pair could be clearly differentiated. The karyotype formula for P. femoralis could be deduced as:
2n (diploid) 44 = L₂₀^m+L₈^sm+L₂^a+M₂^sm+S₄^m+S₄^sm+S₂^a+sex chromosomes