An electronic booking system (Choose and Book – C&B) for general practices making hospital outpatient appointments was introduced in England in 2005 and by 2009 accounted for 50% of appointments. It was intended, inter alia, to reduce the rate of non-attendance at outpatient appointments (7.1% in 2004). We test whether it did so using a 2004-2009 panel with 7900 English general practices. We estimate that the use of C&B was associated with a reduction in non-attendances of 85,600 (15.8%) and a reduction in referrals of 358,000 (3%) in 2009
