The objectives were to characterize repeat breeding in dairy cows, including reproductive performance and risk factors Data from 613 Holstein Friesian cows in nine daily herds across Japan were enrolled A repeat breeder was defined as a cow that did not become pregnant after three inseminations, despite no clinically detectable reproductive disorders In contrast, cows that became pregnant within three inseminations were considered to have normal fertility Of the 613 cows, 87.3% eventually became pregnant after repeated Al (maximum calving to conception interval was 435 d) Mean (+/- SEM) first Al conception rate, clays in milk at first Al, calving to conception interval and service per conception were 38 3%, 82 +/- 2 d, 125 +/- 3 d, and 20 +/- 0 1 times. respectively Normal fertility cows (n = 479) required only 114 3 d to conceive and 1 7 +/- 0 1 inseminations per pregnancy, whereas repeat breeders (n = 86) required significantly more days to conceive (211 +/- 10) and more inseminations per pregnancy (4 7 +/- 0.2) Based on survival analysis. it took 94 d after calving for 50% of normal fertility cows to become pregnant, compared to 155 d for repeat breeders For repeat breeders, 31 4, 50 0, and 58 1% became pregnant within 210, 300, and 435 d after calving, respectively The risk factors for repeat breeding were parity (relative risk [RR] = 0 809, P = 0 058), resumption of postpartum ovarian cycles (RR = 1 928. P = 0 009), and days in milk at first Al (RR = 0991. P = 0 039) In conclusion, repeat breeder dairy cows had very poor reproductive performance Lower parity, abnormal resumption of postpartum ovarian cycles, and shorter clays in milk at first Al were risk factors for repeat breeding. (c) 2010 Elsevier Inc All rights reserved