Dairy animals are very important for production in Egypt. The transition period is a critical period for animals which undergo different hormonal and biochemical changes. The present study was established to evaluate the effect of the transition period on some physiological and biochemical parameters in dairy cows. A number of 30 pregnant dairy Holstein cows were used for this study. Samples of animals were collected at the 2^nd, 4^th, and 6^th week before calving, and at the 2^nd, 4^th, and 6^th week after calving with a two-week interval. Also, samples from ration and water delivered to animals were collected for analysis of their contents. The result of the present study revealed a significant (p<0.05) increase in the level of progesterone, estrogen, prolactin, glucose, and MDA with a significant decrease in the level of cortisol, GSH, SOD, Ca, and P at the 2^nd week before calving, compared to the 6^th week before calving. There was a significant decrease (p<0.05) in the level of progesterone, estrogen, glucose, SOD, Ca, and P with a significant increase in insulin and prolactin levels at the 2^nd week after calving compared to the 6^th week before calving. Lastly, there was a significant increase in progesterone, estrogen, cortisol, glucose, and haptoglobin with a significant decrease (p < 0.05) in the levels of prolactin and GSH in the 2^nd week after compared to the 6^th week after calving.