UK national recommendations include 24 h non-resident availability of consultants with a sessional commitment to intensive care (intensivists). We tested whether continual availability of such specialists improved standardised mortality ratios compared with non-specialist cover by anaesthetists who also cover other hospital departments. The case-mix-adjusted hospital mortality of intensive-care patients improved significantly in the intensivist group compared with the non-specialist group (standardised mortality ratios 0.81 vs 1.11 ratio 0.73 [95% CI 0.55-0.97]). Introduction of 24 h intensivist cover, therefore, seems to improve outcomes in intensive-care units.