Objective: to study the impact of maternal obesity on the outcome of labour. Setting: Al zahraa University hospital.Design: prospective randomized control study.Patients: a total of (80) pregnant women were included in this study from April 2009 to March 2010. Patients and Methods:According to the BMI the patients were classified into two groups. Group (I): (Control Group):Included (30) patients with (body mass index) (BMI) ranging from 20 to 25 kg/m².Group (II): (Obese Group): Included (50) patients with (BMI) ranging from 25 to 30kg/m². Each patient were subjected to full clinical examination (General) Abdominal and pelvic) U/S pelviabdominal examination that is to confirm the inclusion and exclusion criteria of the study. Results : A significant differences was noticed between 2 groups as regard the BMI. The current study showed significant difference in cases subjected to induction of labour with p-value < 0.001. Also significant difference between control group and obese group regarding failed induction, failure to progress 1^st stage, 2^nd stage, shoulder dystocia with p-value < 0.01.Case of C.S showed the highest significant diff. with P-value < 0.0001 .In the present study no sig. diff. between cases of both groups as regard 3^rd stage complication, 4^th stage (PPH) and blood transfusion with P-value 0.658, 0.684 and 0.658 respectively. A high significant diff. between the two groups as regard case of macrosomia, Apgar score < 7 1^st minute, and birth injury with p-value < 0.01. A significant diff. were showed between the cases of both groups as regard the incubation with p-value > 0.05.No significant diff. were noticed between the 2 groups as regard the cases with Apgar score < 7 at 5 minutes with p-value 0.06. A positive correlation coefficient  between the BMI (25-29), (29-33) kg/m² with the case of induction of  labour, failure to progress 1^st stage, shoulder dystoca, cesarean section and fetal low Apgar score. While a  negative correlation was recorded between the BMI of the control group and all the adverse outcomes. Conclusion:Obesity of the gravid women is a sensitive  predictor of the adverse outcome during pregnancy, labour, and post partum. Researches are needed into effective, applicable and acceptable community -based program for obese women planning a pregnancy.