Reports and guidelines concerning intensive care practice have been issued recently.

However, the introduction of such centrally issued recommendations may be difficult because of marked heterogeneity between intensive care units.

This study examined the facilities (number of beds, consultant sessions, nursing establishment), annual workload (number and types of patients admitted) and outcome (intensive care unit mortality) in the (old) Anglia Region.

There were significant differences in the distribution of patients'ages, severities of illness, diagnoses, durations of admission and outcomes.

Such heterogeneity may make multicentre trials more difficult to conduct and create problems when uniform measures designed to improve intensive care services are being planned.