Background: The annual procedure volume is an accepted marker for quality of care and has been documented in various medical fields. Surgeon volume has been shown to correlate with morbidity and mortality in surgical and high risk medical procedures. Though cesarean delivery is one of the most common surgical procedures in the USA, the link between surgeon's annual cesarean delivery volume and maternal outcome has never been tested. Objective: To evaluate the impact of surgeons' annual volume on short term maternal outcome in cesarean deliveries. Study Design: Retrospective cohort study in a single tertiary center between 2006 and 2013. Cesarean deliveries were categorized into two groups based on the annual volume of cesarean delivery of the attending obstetrician. LOW group included low annual volume obstetricians, whose annual volume of cesarean delivery was lower than median. HIGH group comprised high annual volume obstetricians whose annual volume was median and above. Data were collected for all cesarean deliveries; stillbirth and cesarean hysterectomy were excluded. Further analyses were done for quartiles and for four clinical relevant groups according to the annual number of cesarean delivery performed/supervised by the attending (20 or less, 21-60 , 61-120 and more than 120) in regards to the primary outcome. Data were collected for all cesarean deliveries; stillbirth and cesarean hysterectomy were excluded. The primary outcome was a composite adverse maternal outcome including one or more of the following: urinary or gastrointestinal tract injuries, hemoglobin drop > three gm/dL, blood transfusion, re-laparotomy, puerperal fever, prolonged maternal hospitalization and readmission. Secondary outcomes were operative times (skin incision to delivery and overall). Results: A total of 11,954 cesarean deliveries were included, the median annual number of cesarean delivery performed/supervised performed by one obstetrician was 48. Unadjusted bivariate analysis suggested that HIGH group patients, had fewer urinary and gastrointestinal 5