An experiment was conducted to examine the effects of supplementary light intensity level on the reproductive performance of artificially-inseminated Domyati duck hens at different ages. One hundred and four. eighteen-week-old Domyati ducks were randomly distributed into four groups of 6 duck drakes and 20 duck hens each, housed separate in floor pens, and exposed to a daily photoperiod of 17 hours up to the end of the experimental period at 60 weeks of age. To maintain this daily 17-hour photoperiod. the length of natural daylight was supplemented with artificial light, providing light intensity levels of 1.5 (served as a control), 10, 45 or 90 lux at birds' head level of the four experimental groups respectively. At 32, 40 and 60 weeks of age, drakes' semen was collected and evaluated (as ejaculate volume, sperms‘ mass and advanced motility, sperms concentration, and percentage of dead, abnormal, coiled-tail and clumped Sperms), duck hens were artificially-inseminated, and eggs fertility and hatchability were determined. Regardless of age, increasing supplementary light intensity level from 1.5 to 90 lux significantly increased eggs fertllity and hatchability, and improved semen quality traits, but had no effect on ejaculate volume. Apart from the effect of supplementary light intensity level, similar improvement was observed in drakes' semen quality with advancing age from 32 to 60 weeks. Inconsistent improvement was observed, however, in eggs fertility and hatchability as experimental birds advanced in age. At 32 and 60 weeks of age significantly higher egg fertility percentages were observed than at 40 weeks, whereas at 32 and 40 weeks of age significantly higher hatchability percentages were obtained than at 60 weeks. The effects of supplementary light intensity level and age were significantly interrelated for eggs fertility and hatchability, as well as for all semen quality traits studied. except for ejaculate volume and percent of dead sperms. The best economic efficiency of incubation process was obtained at 40 weeks of age With duck exposed to a supplementary light intensity level of 10 lux. It would be concluded that; economically, the use of a supplementary light intensity level of 10 lux is sufficient to achieve satisfactory percentages of fertility and hatchability for eggs of artificially-inseminated Domyati ducks. Most of semen quality traits were also improved under this supplementary light intensity level.