Objective  To examine the effect of surgeon sex on postoperative outcomes of patients undergoing common surgical procedures.

Design  Population based, retrospective, matched cohort study from 2007 to 2015.

Setting  Population based cohort of all patients treated in Ontario, Canada.

Participants  Patients undergoing one of 25 surgical procedures performed by a female surgeon were matched by patient age, patient sex, comorbidity, surgeon volume, surgeon age, and hospital to patients undergoing the same operation by a male surgeon.

Interventions  Sex of treating surgeon.

Main outcome measure  The primary outcome was a composite of death, readmission, and complications. We compared outcomes between groups using generalised estimating equations.

Results  104 630 patients were treated by 3314 surgeons, 774 female and 2540 male. Before matching, patients treated by female doctors were more likely to be female and younger but had similar comorbidity, income, rurality, and year of surgery. After matching, the groups…