The present experiment aimed to estimate mRNA transcriptions of IFITM1 and RSAD2 in the peripheral blood of Chinese Holstein dairy cows during early pregnancy.Peripheral blood at five different time points (0 d,14 d,18 d,21 d,and 28 d) after artificial insemination (AI) were collected.Real-time PCR was employed to detect the relative gene expressions of IFITM1 and RSAD2,while plasma P4 was detected by Chemiluminescence Immunoassay (CLIA) at the same time.Transcriptions of RSAD2 were evaluated in the whole blood of heifers with spontaneous cycles of estrus and/or synchronization of estrus.In addition,typical peripheral blood leukocyte subsets (lymphocyte,natural killer cell,and monocyte) were isolated at 0 d,18 d,and 21 d after AI and gene transcriptions of RSAD2 were detected.The results showed that pregnant cows had significant higher (P＜0.05) plasma P4 levels than non-pregnant cows at 21 d and 28 d.At 14 d and 18 d,transcriptions of bovine IFITM1 in peripheral blood were significantly declined compared with cows at 0 d (P＜0.05),but there was no significant difference between pregnant cows and non-pregnant cows.Although transcriptions of RSAD2 in pregnant cows were elevated significantly at 21 d (P＜0.05),expressions of RSAD2 in pregnant heifers were significantly higher than those in non-pregnant cows as early as 18 d.Further analysis discovered that transcriptions of RSAD2 in pregnant cows with spontaneous cycles of estrus were significant higher than those in non-pregnant cows at 18 d.There was a same trend in cows with synchronization of estrus,but the difference was not statistically significant.At 18 d and 21 d,there was no significant difference of RSAD2 expression in the blood leukocyte subsets between the pregnant cows and non-pregnant cows.These results indicated that transcriptions of bovine IFITM1 was not reliable for early pregnancy diagnosis,while RSAD2 could be applied in bovine pregnancy diagnosis at 18 d in heifers.Further study on the standard which could increase the sensitivity of the test is needed.