The hangul Cervus hanglu hanglu, a Critically Endangered mountain ungulate of Jammu and Kashmir, India, faces the imminent threat of population loss and extinction. Effective management of its largest viable population in Dachigam National Park in the Kashmir Himalaya requires reliable demographic information. Using 14 microsatellite markers we identified 293 individuals (208 females and 85 males) through faecal analysis, and generated data on the genetic status and population size of the hangul in its winter habitat. The mean expected and observed heterozygosities of 0.62 and 0.59 are comparable to those of several red deer Cervus elaphus populations elsewhere. The effective population sizes were 46.3 and 93.7 when the frequencies of rare alleles were considered to be 0.050 and 0.010, respectively. The average mean kinship of the population was 0.34, and there was no evidence of a recent bottleneck event. In genetic mark–recapture analysis the best model included an effect of sex on both detection and recapture probabilities. Detection of males was highest in November, coinciding with the hangul breeding season, whereas detection of females was highest in December. Our estimate of the hangul population using genetic mark–recapture with bootstrapping was 394 individuals. To our knowledge, this is the first study to use genetic data to estimate the population of the hangul. It will guide future studies of this subspecies and also serve as an impetus for identifying founder animals for captive breeding, and for connecting the population in Dachigam National Park with the other small, isolated populations to ensure the long-term survival of this subspecies.