This study was performed to investigate the relation between birth weight and survivability on the production of cloned Hanwoo calves. The 580 cloned embryos were transferred into the 293 recipients. The pregnancy rate of the cloned embryos was 72.3% at 50 days after embryo transfer, and then the rate was dramatically decreased. The mean gestation lengths were 287 days in both clone (range of$279{sim}295$ days) and artificial insemination (AI, range of $255{sim}293$ days) calves, respectively. The mean birth weight of cloned calves (30.3kg) was significantly higher compared to that of AI calves (23.7kg) (p<0.05). Among the cloned calves, the birth weight was not different in both normal delivery (n=17, 29.9kg) and caesarean section (n=14, 32.3kg). The weight, however, was significantly higher in the clones (n=18, 32.8kg) dead within 175 days than that of the clones (n=11, 28.3kg) alive more than 175 days after birth (p<0.05). Interestingly, all cloned calves weighed <15kg (n=5) or >35kg (n=9) at birth have been dead within 175 days from the date of birth. The causes of death in the cloned calves were premature birth (n=2, 10.0%), abnormal function of lung and liver (n=2, 10.0%), abnormal function of lung (n=4, 20.0%), malformation (n=4, 20.0%), unknown (n=4, 20.0%), and sudden death syndrome (n=4, 20.0%), respectively. Our findings suggest that normal birth weight is one of the most important factors to survive more than 6 months in cloned calves.