The objective of this study is to investigate the changes in concentrations of leptin and insulin in serum of Korean cattle (Hanwoo) with reproductive disorders and to examine the relationship among leptin, insulin, and body condition score (BCS). The concentration of leptin in serum of pregnant Hanwoo showed insignificant difference from that in serum of Hanwoo with reproductive disorder, such as repeat breeding, follicular cyst, corpus luteum cyst, ovarian atrophy, and feeble estrus (p>0.05). However, the concentrations of leptin and insulin in serum were changed with different BCS value. In emaciated Hanwoo (BCS $2.0sim2.9$), they were significantly decreased compared to BCS $3.0sim3.4$ (p<0.05). The leptin showed different genotypes with different BCS value. In BCS $2.0sim2.9$, C/T genotype was expressed (83.3%) more than C/C (16.7%) or T/T (0%) genotype, whereas C/C genotype was expressed (62.5%) more than C/T (25.0%) or T/T (12.5%) genotype in BCS $3.5sim4.0$. The insulin concentration in follicular fluid obtained from ovary with follicular cyst which has follicles having diameter of $25sim40 mm$ was significantly higher (p<0.05) than those in normal follicle fluid which has follicles having diameter of $3sim10 mm$. These results showed that concentration of leptin and insulin in serum were related to BCS value and follicular size and suggest that the changes in concentration of leptin and/or insulin in serum could be a potent biomarker for diagnosis of bovine reproductive disorder.