Unexpected incidents are common in intensive care medicine. One means of detecting, diagnosing, and treating these events is use of physiologic displays that show the patients’ vital signs. Monitors currently in use in intensive care units (ICUs) provide information in numerical and waveform formats, but most such displays originated in patient monitors developed for use by anesthesiologists. The present study focused on problems related to patient monitoring and needs of ICU nurses. Semistructured interviews of 26 experienced ICU nurses were employed to identify monitor usability problems. Among their comments, interviewed nurses mentioned that monitors now in use make it difficult to access vital sign trends and do not permit marking of events or interventions on trend displays. The present results indicate that patient monitoring in the ICU could be improved, but that such improvement will require identification of the tasks nurses perform and the development of new monitoring tools that fit their specific needs.