Objectives: to evaluate the effect of dexamethasone on labor duration and to establish whether dexamethasone plays a role in shorting the duration interval between initiation of labor induction and beginning of the active phase of labor in primigravida full-term pregnancy. Study design: Case control study included 120 primigravidae with full-term pregnancy classified into two groups: group I (cases) included 60 women assigned to receive a single 8-mg dose of dexamethasone intra-muscular and group II (control) included 60 women will not receive dexamethasone or any other cervical ripening agent. Results: The interval between initiation of labor induction and beginning of active phase of labor was shorter in the dexamethasone than in the control group (2.54±0.94 hours vs. 3.59±0.86 hours; p=0.001). Dexamethasone group shows shorter duration of active phase of labor than control group (4.82±0.56 hrs. vs. 5.12±0.58 hrs.). Dexamethasone group shows shorter duration of first stage of labor than control group (7.35±1.15 hrs. vs. 8.69±1.09 hrs.). Dexamethasone group shows faster rate of cervical dilatation than control group (1.37±0.18 cm/hr. vs. 1.28±0.17 cm/hr.). Dexamethasone group shows shorter duration of second stage of labor than control group (25.09±12.99 minutes vs. 30.73±12.96 minutes). Oxytocin requirement in dexamethasone group was less than in control group (5.35±1.49 hrs. vs. 5.97±1.34 hrs.). Conclusions: The administration of dexamethasone found to shorten labor duration.