This study was carried out to investigate the changes of blood chemical values in 61 crossbred calves at 1 day, 1 week, 2 weeks, 4 weeks and 9 weeks of age, respectively. The blood chemical values of calves with diarrhea were compared with those of normal calves, and blood chemical values were compared for groups of calves with weight gain divided into four ranges; up to 0.9 kg/wk and over 7.0 kg/wk. The results obtained in this study show that the mean values and standard deviation of red blood cell (RBC) and packed cell volume (PCV) of normal calves at 1 day of age (806.7$pm $56.5 10$^{4}$/$mu$l and 33.8$pm $5.2 %) decreased at 1 week of age and increased at 2 and 4 weeks of age. The PCV of normal calves at 9 weeks of age (32.6$pm $2.3 %) was significantly lower than that at 2 and 4 weeks of age (p<0.05). Total protein of normal calves at 1 day of age (6.8$pm $0.5 g/100 ml) decreased to 6.4$pm $0.6 g/100ml at 1 week and increased to 7.0$pm $ 0.7 g/100 ml at 2 weeks. After 2 weeks of age, total protein tended to decrease gradually to 9 weeks of age. Glucose of normal calves at 9 weeks of age (78$pm $4 mg/100 ml) was significantly lower than that at 1 week (110$pm $8 mg/100 ml) (p<0.01). At all ages, RBC, white blood cell (WBC), PCV and fibrinogen of calves with diarrhea were higher than those of normal calves. RBC and PCV of calves with diarrhea at 1 week of age (929.7$pm $39.7 10$^{4}$/$mu$ and 42.3$pm $0.4 % were significantly higher than those of normal calves at 1 week (786.4$pm $80.9 10$^{4}$/$mu$l and 32.2$pm $3.8 %) (p< 0.05), which suggest that diarrhea at this age can be dangerous. The weekly weight gain was an average of 4.2 kg/wk from birth to 9weeks. RBC, PCV, fibrinogen, total protein and vitamin E of calves with weight gain more than 4.0kg/wk. From the above results we obtained eledata support the importance of providing high quality feed from 4 weeks to 9 weeks of age for satisfactory weight gain of calves.