OBJECTIVE: To describe pediatric critical care nurses' knowledge of dysrhythmias in critically ill pediatric patients and relate this knowledge level to certain demographic variables (education, nursing experience, certification, supplemental training, area of employment and geographic region of residence). DESIGN: A descriptive survey. SETTING: American Association of Critical-Care Nurses' 19 geographic regions of the United States. PARTICIPANTS: Of 1000 questionnaires mailed to pediatric critical care nurses who were members of the American Association of Critical-Care Nurses in 1991, 356 responses were received (a response rate of 36%). INTERVENTION: A criterion-referenced, self-administered test regarding pediatric dysrhythmias and a demographic sheet randomly mailed to 1000 pediatric critical care nurses. Test results were analyzed and compared with demographic variables. RESULTS: The mean total test score was 66%. Significantly higher total test scores and selected subtest scores were demonstrated in relationship to the following variables: increased age; certification in pediatric advanced life support, advanced cardiac life support or adult critical care; increased years of adult critical care experience; advanced dysrhythmia courses and dysrhythmia self-study; and perceived knowledge level above that of the advanced beginner. CONCLUSIONS: Pediatric critical care nurses' overall knowledge of dysrhythmias was low. Knowledge strengths included recognition of basic and life-threatening dysrhythmias and calculation of basic ECG measurements. Knowledge deficits included importance of sinus bradycardia in the neonate, appropriate intervention for life-threatening dysrhythmias and calculation of an irregular heart rate. These deficits should be considered when planning continuing education programs for pediatric critical care nurses.