New instrumentation, techniques and computers have made such large amounts of information rapidly available to ICU clinicians that there is now a danger of information overload. To help with this problem at LDS Hospital, a computerized system was implemented in the Shock-Trauma ICU. This ICU is almost totally computerized with each patient's physiologic, laboratory, drug, demographic, fluid input/output and nutritional data integrated into the patient's computer record. In the ICU, physician decision-making takes place in two situations: during rounds and on-site. For this study, data usage in decision-making was evaluated in both of these environments. The items of data used in decision-making were tabulated into six categories: bedside monitor, laboratory, drugs, input/output and IV, blood gas laboratory, observations and other. Comparisons were made between the portion of the computerized database occupied by a category and its use in decision-making. Combined laboratory data (clinical, microbiology and blood gas) made up 38 to 41% of total patient data reviewed and occupied 16.3% of the database. Observations made up 21-22% of the data reviewed and occupied 6.8% of the database. Drugs, input/output and IV data usage ranged from 13% to 23%, but occupied 36% of the database. Bedside monitor data usage was 12.5% to 22% and occupied 32.5% of the database. The 'other' category, used 2.5% to 5% of the time, made up 8.4% of the database. These results indicate that patient data collection and storage must be evaluated and optimized. This evaluation, along with implementation of the computerized ICU Rounds Report developed for optimal data presentation, will help physicians to evaluate patient status and should facilitate effective decisions.