This investigation aimed at studing the cyclic and acyclic patterns of ovarian function in Friesian cattle. Twenty-one pregnant Friesian cows were taken randomly from a herd located at sakha experimental station, Animal Production Research Institute, Ministry of agriculture, Egypt. Cows were experimented 15-20 days before the expected calving day till two months after fertile insemination. Blood samples were withdrawn twice weekly at 3 - 4 days intervals. Plasma was used for assaying progesterone levels imploying radioimmunoassay. Heat detection was performed twice daily in all cows preconception. Results revealed that the overall mean of postpartum anestrus period was 80.4 days. During this period plasma progesterone was recorded at basal level (<0.5 ng/ml), postpartum anestrus period was prolonged in the highly milk producing cows compared to low producers (91.88 versus 61.23 days). The difference between low and high lactating cows in this respect was statistically insignificant. Overall average length of postpartum to first ovulation interval was 116.3 days. Postpartum to the first ovulatory estrus interval averaged 127.0  days, while days open averaged 186.1 days. Milk production had a significant (p < 0.01) effect on postpartum to first ovulation and to first estrus intervals. Number of ovulations and inseminations /conception was 3.9 and 2.35, respectively with insignificant effect of milk production on both traits. The percentage of quiet ovulation was 41.7%. This percentage was 71.4% , 42.1% and 27.3%  in the first, second and third postpartum ovulation, respectively. Forty one percent of the short low peak progesterone cycles was 9.79 days in length with an average progesterone peak of 2.2 ng/ml. Overall average length of regular normal progesterone cycles was 22.36 days with average progesterone peak of 6.37 ng/ml.