Background High profile safety failures have demonstrated that recognising early warning signs of clinical and physiological deterioration can prevent or reduce harm resulting from serious adverse events. Early warning scoring systems are now routinely used in many places to detect and escalate deteriorating patients. Timely and accurate vital signs monitoring are critical for ensuring patient safety through providing data for early warning scoring systems, but little is known about current monitoring practices. Objective To establish a profile of nurses’ vital signs monitoring practices, related dialogue, and adherence to health service protocol in New South Wales, Australia. Methods Direct observations of nurses’ working practices were conducted in two wards. The observations focused on times of the day when vital signs were generally measured. Patient interactions were recorded if occurring any time during the observation periods. Participants (n = 42) included nursing staff on one chronic disease medical and one acute surgical ward in a large urban teaching hospital in New South Wales. Results We observed 441 patient interactions. Measurement of vital signs occurred in 52% of interactions. The minimum five vital signs measures required by New South Wales Health policy were taken in only 6–21% of instances of vital signs monitoring. Vital signs were documented immediately on 93% of vitals-taking occasions and documented according to the policy in the patient's chart on 89% of these occasions. Nurse–patient interactions were initiated for the purpose of taking vital signs in 49% of interactions, with nurse–patient discourse observed during 88% of all interactions. Nurse–patient dialogue led to additional care being provided to patients in 12% of interactions. Conclusion The selection of appropriate vital signs measured and responses to these appears to rely on nurses’ clinical judgement or time availability rather than on policy-mandated frequency. The prevalence of incomplete sets of vital signs may limit identification of deteriorating patients. The findings from this study present an important baseline profile against which to evaluate the impact of introducing continuous monitoring approaches on current hospital practice.