This study aimed at investigating the knowledge level of cattle breeders regarding some diseases affecting calves mortality during suckling period in some villages of El-bostan area. The specific objectives were: 1-assessing  the cattle breeders' knowledge level regarding some diseases infect calves during suckling period (diseases symptoms and methods of protection), 2-studying the relationship between identified knowledge level and some socio –economic characteristics of the interviewed breeders, and 3- determining some problems that face cattle breeders during stages of pregnancy, parturition and weaning of  cattle. The research data was collected by using elaborately Questionnaire through interviewing 100 cattle breeders as a representative sample in the selected three villages in El-bostan area. Main statistical methods used for data analysis included;  Tabular presentation, means, standard deviation, percentage distribution, simple correlation, and multiple regressions. The major findings of this study indicated the following: 1-    Assessment of cattle breeders  level of  knowledge regarding some  diseases that   infect calves during suckling period  revealed that  about  64%  of  respondents were  rated  either  “medium" or “low". 2-    Findings  pertaining to the relationship between  cattle breeders' level of knowledge  regarding some  diseases that   infect calves during suckling period and selected socio- economic characteristics indicate that  the studied independent variables namely; health and environmental awareness, application of some animal extension  recommendations, animal farm size, and participation  in agricultural extension activities had  positive effect on knowledge level of cattle breeders. The multiple regression analysis also revealed that only one variable “health and environmental awareness" accounted for 32% of the variance in respondents' level of knowledge as the central variable of the study. 3-    Problems and obstacles which met the studied cattle breeders during stages of pregnancy, parturition and weaning of their cattle were mainly the high cost of both "Veterinary services", and "feeding animals on concentrates" .