The distribution and reproduction of Hediste diversicolor were studied in the Barge canal of Damietta Harbor by taking monthly samples at three stations for one year. Temporal and spatial variations of some water quality parameters and sediment conditions were analyzed. The highest densities occur in the middle of the canal at station II, establishing it as a suitable zone for worm production. The seasonal pattern of density showed peaks during the summer and autumn months with significant differences between stations. Females were a preponderance giving an annual sex ratio of 2.5(females):1(males). The maximum body length (9.8 cm) and weight (0.79g) appeared at station II. The formula of the length-weight relationship indicated allometric growth. The spawning season was long, the worm can breed all the year-round, with however a maximum during spring. Mature oocyte stages were limited to certain seasons at station I with increased pollution impact, whereas continuous mature oocyte occurrence was observed at stations II and III. The results reflected differences in population and reproductive responses among Barge canal parts, suggesting that pollution and ecological status should be considered in the evaluation of polychaetes population dynamics.