To obtain an understanding of how Hospital in the Home (HITH) nurses recognise and respond to clinical deterioration in patients receiving care at home or in their usual place of residence. Recognising and responding to clinical deterioration is an international safety priority and a key nursing responsibility. Despite an increase in care delivery in home environments, how HITH nurses recognise and respond to clinical deterioration is not yet fully understood. A prospective, descriptive exploratory design was used. A survey containing questions related to participant characteristics and 10 patient scenarios was used to collect data from 47 nurses employed in the HITH units of three major health services in Melbourne, Australia. The 10 scenarios reflected typical HITH patients and included medical history and clinical assessment findings (respiratory rate, oxygen saturation, heart rate, blood pressure, temperature, conscious state and pain score). The three major findings from this study were that: (i) nurse and patient characteristics influenced HITH nurses' assessment decisions; (ii) the cues used by HITH nurses to recognise clinical deterioration varied according to the clinical context; and (iii) although HITH nurses work in an autonomous role, they engage in collaborative practice when responding to clinical deterioration. Hospital in the Home nurses play a fundamental role in patient assessment, and the context in which they recognise and respond to deterioration is markedly different to that of hospital nurses. The assessment, measurement and interpretation of clinical data are a nursing responsibility that is crucial to early recognition and response to clinical deterioration. The capacity of HITH services to care for increasing numbers of patients in their home environment, and to promptly recognise and respond to clinical deterioration should it occur, is fundamental to safety within the healthcare system. Hospital in the Home nurses are integral to a sustainable healthcare system that is responsive to dynamic changes in public health policies, and meets the healthcare needs of the community.