The monotypic genus Leontochir Phil. (Alstroemeriaceae Dumortier), represented by Leontochir ovallei, is endemic to Chile, and its geographical distribution is restricted to the coastal zone of the Atacama Desert (28°S). In previous cytogenetic studies on L. ovallei a diploid karyotype 2n = 2x = 18 was described. In this work a first analysis of the C-banding pattern of L. ovallei is presented. L. ovallei showed large regions of constitutive heterochromatin within the karyotype, with C-bands on all chromosome pairs except 9. The relative length of the C-bands was 20.0% of the total haploid set length. The presence of large regions of constitutive heterochromatin on the chromosomes was concurrent with the presence of many conspicuous and large chromocenters in the interphase nuclei. According to these results, L. ovallei shows the largest value of relative C-band length so far described within the Alstroemeriaceae. These cytogenetic results on L. ovallei increase the available data on C-banding patterns in Alstroemeriaceae with an additional genus.