Background: In open grazing dairy cattle farming, it is critical to identify and monitor health status and disease incidence. Testing of physiological parameters is essential to monitoring the health status of dairy herds. Therefore, the present study was carried out to evaluate the comparative status of serum chemistry and corresponding milk chemistry in cattle reared in open grazing system. Methods: The research was conducted in 10 clinically healthy cows reared under open grazing system from different commercial farms of Baghabari in Sirajganj district. Blood samples were collected from individual animal through the jugular vein puncture. Corresponding milk samples were collected directly from teat during the morning milking time. Blood and milk samples were brought to the laboratory in an ice cooled sample transportation box. Total serum protein, glucose, cholesterol, calcium, phosphorus, sodium, potassium, chloride concentration and corresponding milk protein, lactose, cholesterol, calcium, phosphorus, sodium, potassium, chloride concentration were measured by using standard analytical techniques. Results: Results showed that, there was a partially positive correlation among blood glucose and milk lactose (0.698), blood cholesterol and milk cholesterol (0.709), blood sodium and milk sodium (0.657). In addition, a strongly positive correlation was found between blood calcium and milk calcium (0.905). However, partially negative correlation between blood phosphorus and milk phosphorus (-0.688) was observed. Conclusions: The study shows the prospect of effectively using comparative analysis of serum and corresponding milk constituents to construct a comprehensive model or technology for the betterment of dairy farming in Bangladesh.