We evaluated the impact of the World Health Organization Obstetric Safe Surgery Checklist (WHO Checklist) on perioperative communication between anaesthetists and obstetricians by performing a retrospective audit in a Teaching hospital in London, UK. Caesarean section births from February to March 2009 and April to May 2011 were studied. Caesarean section notes from obstetricians and anaesthetists managing the same woman during the study period were reviewed. Grading differences between obstetricians and anaesthetists before and after checklist introduction were evaluated. Communication failure (where obstetricians and anaesthetists had documented different caesarean section grades [level of urgency]) and good communication (where obstetricians and anaesthetists had documented the same caesarean section grade) were observed. In total, 195 caesarean sections before introduction of the WHO safe surgery checklist and 194 caesarean sections after checklist introduction were studied. Grading differences occurred in 24.1% of caesarean sections without checklists compared with 10.3% with checklists (P < 0.001). During emergency caesarean section alone, grading differences between obstetricians and anaesthetists were smaller, although this was not significant (P = 0.222). We conclude that implementation of a WHO Obstetric Safe Surgery checklist improves the communication of caesarean section grade (urgency) between obstetricians and anaesthetists.