To obtain the basic data for blood chemistry, the effects of the time elapse of serum separation on bovine blood chemical values were investigated. The results obtained are summerized as follows : 1. The constant fluctuation tendency and significance was not detected in GOT, GPT, BUN, Creatinine, ALP, CPX, Cholesterol, Ca, Mg and Pi. 2. Glucose showed the decrease tendency according to the time elapse of serum separation. As the values at 12 and 24 hours showed significant lower values than those at 1 and 2 hours (p＜0.01) it was thougth that separation time of serum should be focussed for the glucose determination.