Bovine Herpesvirus 1 (BoHV-1) causes infections with many clinical signs, including rhinotracheitis, encephalitis, and genital lesions. The virus occurs worldwide in bovines, and in recent years, it has been reported in yaks (Bos grunniens) inhabiting the Tibetan Plateau in China. However, there is little epidemiologic data describing BoHV-1 infections in China’s yak herds. We conducted a cross-sectional study on the Qinghai–Tibetan Plateau (QTP) in China July 2011–July 2012 to estimate the prevalence of BoHV-1 antibody in yak herds. We collected 1,840 serum samples from yaks on the QTP, in Tibet (988 yaks), Qinghai (475 yaks), and Sichuan (377 yaks) Provinces. Using an enzyme-linked immunosorbent assay, we found that 381 (38.6%) of the Tibetan samples, 212 (44.6%) of the Qinghai samples, and 105 (27.9%) of the Sichuan samples had detectable antibodies to BoHV-1. Given that this high prevalence of infection in yaks could result in heavy economic losses, we suggest that an effective management program, including vaccination and strategies for infection control, be developed.