Patient survival often depends on decisions by nurses to call emergency assistance. The experiences of nurses calling emergency assistance have not been described. This descriptive study explored the experiences of registered nurses (n=32) using unstructured interviews. The main findings were that nurses questioned whether they were doing the 'right thing' calling the emergency team, sometimes collaborated with others prior to calling and most felt nervous and anxious. They recognized patient deterioration from feelings they had that something was wrong. However, they were not able 'to put their finger on it'. Knowing the patient and past experiences were involved in the recognition of deterioration. This association indicates the importance of experience in the development of clinical decision-making skills. Further, nurses calling emergency assistance need to be provided with the opportunity to debrief after calling. Their heavy reliance on subjective data before searching for objective data as outlined in the emergency calling criteria suggests that it is essential that nurses do not devalue or ignore concerns they may have about patients.