The prevalence of major calf disease was investigated in 117 Holstein dairy calves in Chonnam area. All of them were moved in the College experimental farm which is operated in intensive units. clinical signs were daily examined throughout two months after the introduction of the College farm. Among calves, 92 cases(78.6%) died in the two months after the introduction in it. Outbreaks of respiratory and alimentary diseases were their main causes of their fatality. The incidence of respiratory disorders during the full period of the experiment was up to 42.8%, and the alimentary diseases were occurred 35.9% of the herd. Most of the mortality was related with respiratory(59.9%) and alimentary(52.1%) pathogens. Also calf mortality by combined infection claimed 6.6% among 100 morbidity cases. Principle pathogens to cause mortality were Pasteurella spp(44.4%), E coli(29.9%), bovine viral diarrhea virus(16.2%), IBRV(12.0%), respectively. Viruses also played as an important role in increasing calf morbidity to secondary respiratory bacterial pathogens. Pasteurella infection combined with infectious bovine rhinotracheitis virus(11 cases), parainfluenza virus type-3(9 cases), or bovine respiratory syncytial virus(7 cases) was appeared as major pattern to mortality. colibacillosis in causing enteritis was concurrently infected with BVD(19 cases), bovine coronavirus infection(14 cases), salmonellosis(5 cases), coccidiosis(5 cases) and clostridial infection(4 cases). Ninty-two cases to death were appeared to have 100% neutralizing antibodies to BCV; Among them, 73.8% had the neutralizing antibody level higher than 64. Calves with neutralizing antibodies higher than 16 to BVDV were 50%. The cases with neutralizing antibody level lower than 8 to BEFV were 89.4% that means the necessity of appropriate vaccination.