The frequency of Cryptosporidium infection in yaks from Qinghai province, People's Republic of China, was determined from examination of 1,027 fecal samples collected from 979 adult yaks and 48 yak calves during 4 seasons from 7 geographic areas within the province. PCR amplification of extracted DNA was used to characterize the different species of Cryptosporidium oocysts isolated by fecal examination. Twenty-six (2.53%) positive samples were identified and successfully sequenced: 17 Cryptosporidium ryanae (65.38%), 8 Cryptosporidium bovis (30.77%), and 1 Cryptosporidium baileyi (3.85%). The results of the study indicate that autumn is the primary season for transmission of Cryptosporidium to susceptible yak calves given the favorable temperatures and higher altitude of Qinghai province. To our knowledge, C. baileyi, a species predominately associated with birds (avian hosts), is described for the first time in yaks.