This paper describes the development and application of two integrated models which can be used for assessing the life cycle risk (to life) and environmental impact of a number of possible concept options for new offshore oil and gas developments. The two models can also be used for ranking the designs in terms of lowest human risk and environmental impact. The paper also gives values/criteria for both risks to safety, health and the environment by which the total safety, health and environmental assessment/impact may be balanced as a whole. The paper illustrates the use of the models and shows that the pragmatic or cosmetic improvement to safety, health or the environment may not be advantageous to the overall safety, health and environmental objectives. While the models were developed originally for offshore installations, the basic framework can be readily adapted for use on onshore petrochemical processes. (C) 2002 Elsevier Science B.V. All rights reserved.