Abstract: To find out the diseases occurring in cockerels and its relationship with the management of cockerel`s farm an investigation was carried out from day-old chicks up to marketing at three different cockerel farms in Mymensingh district. In the farm 1, IBD appeared at the age of 31-35 day, the morbidity being 100% and mortality 28.57%. Vaccination at high environmental temperature and use of no fumigation, might be the managemental factors contributed in the causation of the malady. In the farm 2, the morbidity and mortality of yolk sac infection, hypovitaminosis-E, coccidiosis and miscellaneous condition were recorded 3.6 and 2.4%; 4.4 and 2.0%; 8.4 and 0.8%; 0.4 and 0.4%, respectively. However, litter management problem and problem in maintenance of optimum temperature in the shed might be related to these maladies. In the farm 3, the morbidity and mortality rates of the diagnosed diseases like IBD and hypovitaminosis E were 8.6 and 1.4%; 1.2 and 0.4%, respectively. The proportionate mortality of cockerels in these farms were 81.6% for IBD, 8.04% for hypovitaminosis E, 6.89% for yolk sac infection, 2.29% for coccidiosis and 1.14% for miscellaneous condition. IBD occurred in age group of >2-8 weeks, hypovitaminosis E in 0-2 and >2-8 weeks group, yolk sac infection in 0-2 weeks, coccidiosis in >8-20 weeks and the miscellaneous condition in 0-2 weeks group. The findings indicate that IBD is the major disease problem in cockerel farming in Mymensingh.