Caesarean section rates have risen in recent years and this has led to concern. Significantly different Caesarean section rates have been reported between different teaching hospitals. This study compares the Caesarean section rates between 2 Sydney teaching hospitals draining populations from different areas of Sydney. Raw figures showed significantly different Caesarean section rates (22.5% at Royal North Shore Hospital compared with 18.3% at Westmead Hospital). Each hospital has a significantly different case mix when maternal ages are compared. When Caesarean section rates were corrected for maternal age and parity, there was no significant difference. As maternal age is an important factor influencing Caesarean section rates, future reports on obstetric services should consider this factor in making comparisons.