The practice of anaesthesia and its outcome is compared, by means of the Cardiff Anaesthetic Record System, between two periods of 6 years, in whiph 53 541 and 108 878 anaesthetics were administered by the staff of one department. The proportion of emergency cases has increased from 10.6% to 18.7%, but the mortality m hospital has declined from 1 in 35 anaesthetics to 1 in 46