Registered nurses (N = 323) working in a 500-bed tertiary care hospital in a large midwestern city were surveyed to determine what and how they initially learned about the medical devices they use, and the consequences of their use. The most frequently identified methods of initial learning were trial and error (taught self) and reading the user instruction manual. At least 90% of respondents indicated that when they first learned about the device they learned how to operate it and its purpose and function. Medical device use causes more than 75% of staff nurses to feel stressed; 11% had used a medical device that had harmed a patient. ©1995 John Wiley & Sons, Inc.