Broiler breeder Lohmann chickens aged 39 weeks received 3 doses each 0.2 ml of the inactivated oil emulsion AI- H9N2 vaccine, at the 2nd, 7th and 15th weeks of age by subcutaneous injection. The individual HI values of the tested samples were homogenous as their SD values were lower. All breeder and progeny sera were positive (100- 66.7%) at weeks 40- 46 weeks of age. Correlation between parents and progeny HI antibody levels was 0.95. Progeny/Parents HI antibodies percentage were ranged from 54.9 to 65.2%. Correlation between parents and progeny ELISA and HI antibody levels were 0.91 and 0.60- 0.65; respectively. The detected HI antibody titres at the 3rd day of age were slightly increased than that of the 1st day titres followed by gradual decrease to be apparently negative at the 12th -21st day of age in comparison to the original levels. The tested groups for Antibodies to H9 by ELISA test were still detected to 21- 27 days of age of progeny. The half-life time of maternal antibodies expressed as loss of one HI log 2 between groups was ranged from 3.3- 7.2 days; with average 5.1- 5.6 days. Half life time by ELISA titre was in average of 8.9 days. Correlations between HI and ELISA ranged from 0.83-0.94. We concluded that both HI and ELISA tests are of the same value in detection of AI antibodies and first vaccination of broiler chicks with maternal antibodies against AI H9N2 must be done after the 6th day of age.