This study aimed to evaluate the effect of sowing date, varietal susceptibility and egg–parasitoid Trissolcus basalis (Woll.) (Hymenoptera: Scelionidae) on the population size of Nezara viridula L. in soybean field at the Experimental Farm of Sakha Agricultural Research Station, Kafr El-Sheikh governorate during two growing seasons of soybean, Glycine max (L.); 2016 and 2017. Statistical analysis of data revealed that the early sown plants in the first season were more preferable to infestation by N. viridula and late sowing plants in the second season. The variety Giza 111 and Crawford appeared as susceptible (S), while Giza 35, Giza 21 and H30 appeared as low resistant (LR). The biggest peak of parasitism (88.19%) was recorded on 1^st September Throughout 2016 season, while in 2017 season the highest peak (97.01%) was recorded on 24^th July. Also, T. basalis was the only parasitoid emerged from eggs of N. viridula.