Evaluation of serum biochemical constituents during early pregnancy may serve as indicators of early aberrations in physiology and metabolism and therefore appropriate corrective measures can be taken to overcome these disturbances. In this study, important serum metabolites (glucose, total protein, albumin, total cholesterol, triglycerides, blood urea nitrogen, uric acid and creatinine), minerals (calcium, inorganic phosphorus, magnesium, sodium, potassium and chloride) and enzymes (alkaline phosphatase, amylase and lipase) were estimated during early pregnancy stages (day 10 and 21 post-service) and in non-pregnant sows. Our study revealed that majority of the serum constituents did not differ significantly between non-pregnant and early pregnancy stages and also among early pregnancy groups. However, serum levels of blood urea nitrogen (BUN) and sodium significantly increased (p<0.05 and p<0.01, respectively) from non-pregnant to early pregnancy stages. Whereas serum levels of chloride increased significantly (p<0.01) from day 10 to day 21 of pregnancy. This study forms a preliminary step to identify any alterations in serum biochemical constituents during early pregnancy stages in pigs which can be further replicated in large number of animals to establish a reference range for major serum constituents and indicators for any physiological or metabolic disturbances.